diff --git a/packages/basics/src/file-save.js b/packages/basics/src/file-save.js
index d16c35805..beacf6378 100644
--- a/packages/basics/src/file-save.js
+++ b/packages/basics/src/file-save.js
@@ -65,11 +65,11 @@ export default function FILESave(data, feed) {
         this.whenFinish = new Promise((resolve, reject) => {
             const output = compress ? this.input.pipe(createWriteStream(filename)) : this.input;
             output.once('error', (err) => {
-                debug('ezs')(`WARNING: ${filename} not saved. ${err}`);
+                debug('ezs:warn')(`File ${filename} not saved.`, this.ezs.serializeError(err));
                 reject(err);
             });
             output.once('close', () => {
-                debug('ezs')(`${filename} saved.`);
+                debug('ezs:info')(`${filename} saved.`);
                 lstat(filename, (err, stat) => {
                     if (err) {
                         return reject(err);
diff --git a/packages/basics/src/tar-extract.js b/packages/basics/src/tar-extract.js
index 345885394..2b2a7a57d 100644
--- a/packages/basics/src/tar-extract.js
+++ b/packages/basics/src/tar-extract.js
@@ -3,6 +3,7 @@ import micromatch from 'micromatch';
 import { createGunzip } from 'zlib';
 import getStream from 'get-stream';
 import writeTo from 'stream-write';
+import debug from 'debug';
 
 /**
  * Take the content of a tar file, extract some files.
@@ -61,7 +62,7 @@ export default function TARExtract(data, feed) {
                             () => next(),
                         );
                     } catch (e) {
-                        console.warn(`WARNING: file was ignored (${header.name})`, e);
+                        debug('ezs:warn')(`File was ignored (${header.name})`, ezs.serializeError(e));
                         stream.resume();
                         return next();
                     }
diff --git a/packages/basics/src/url-connect.js b/packages/basics/src/url-connect.js
index c82fd6139..787fe848d 100644
--- a/packages/basics/src/url-connect.js
+++ b/packages/basics/src/url-connect.js
@@ -62,7 +62,7 @@ export default async function URLConnect(data, feed) {
             await retry(
                 async (bail, numberOfTimes) => {
                     if (numberOfTimes > 1) {
-                        debug('ezs')(`Attempts to reconnect (${numberOfTimes})`);
+                        debug('ezs:debug')(`Attempts to reconnect (${numberOfTimes})`);
                     }
                     const controller = new AbortController();
                     const response = await fetch(url, {
@@ -108,13 +108,15 @@ export default async function URLConnect(data, feed) {
         }
         catch (e) {
             if (!noerror) {
-                debug('ezs')(
-                    `Break item #${this.getIndex()} [URLConnect] <${e}>`,
+                debug('ezs:warn')(
+                    `Break item #${this.getIndex()} [URLConnect]`,
+                    ezs.serializeError(e),
                 );
                 feed.stop(e);
             } else {
-                debug('ezs')(
-                    `Ignore item #${this.getIndex()} [URLConnect] <${e}>`,
+                debug('ezs:info')(
+                    `Ignore item #${this.getIndex()} [URLConnect]`,
+                    ezs.serializeError(e),
                 );
             }
             output.end();
diff --git a/packages/basics/src/url-fetch.js b/packages/basics/src/url-fetch.js
index 45a87687d..8cb46ef82 100644
--- a/packages/basics/src/url-fetch.js
+++ b/packages/basics/src/url-fetch.js
@@ -74,10 +74,10 @@ export default async function URLFetch(data, feed) {
     } catch (e) {
         controller.abort();
         if (noerror) {
-            debug('ezs')(`Ignore item #${this.getIndex()} [URLFetch] <${e}>`);
+            debug('ezs:info')(`Ignore item #${this.getIndex()} [URLFetch]`, this.ezs.serializeError(e));
             return feed.send(data);
         }
-        debug('ezs')(`Break item #${this.getIndex()} [URLFetch] <${e}>`);
+        debug('ezs:warn')(`Break item #${this.getIndex()} [URLFetch]`, this.ezs.serializeError(e));
         return feed.send(e);
     }
 }
diff --git a/packages/basics/src/url-request.js b/packages/basics/src/url-request.js
index 9b78338c9..a349cbf51 100644
--- a/packages/basics/src/url-request.js
+++ b/packages/basics/src/url-request.js
@@ -81,10 +81,10 @@ export default async function URLRequest(data, feed) {
     const onError = (e) => {
         controller.abort();
         if (noerror) {
-            debug('ezs')(`Ignore item #${this.getIndex()} [URLRequest] <${e}>`);
+            debug('ezs:info')(`Ignore item #${this.getIndex()} [URLRequest]`, this.ezs.serializeError(e));
             return feed.send(data);
         }
-        debug('ezs')(`Break item #${this.getIndex()} [URLRequest] <${e}>`);
+        debug('ezs:warn')(`Break item #${this.getIndex()} [URLRequest]`, this.ezs.serializeError(e));
         return feed.send(e);
     };
     try {
diff --git a/packages/basics/src/url-stream.js b/packages/basics/src/url-stream.js
index dd2b7505e..f4605794e 100644
--- a/packages/basics/src/url-stream.js
+++ b/packages/basics/src/url-stream.js
@@ -78,6 +78,7 @@ export default async function URLStream(data, feed) {
     if (this.isLast()) {
         return feed.close();
     }
+    const { ezs } = this;
     const url = this.getParam('url');
     const path = this.getParam('path', '*');
     const retries = Number(this.getParam('retries', 5));
@@ -103,10 +104,10 @@ export default async function URLStream(data, feed) {
     const onError = (e) => {
         controller.abort();
         if (noerror) {
-            debug('ezs')(`Ignore item #${this.getIndex()} [URLStream] <${e}>`);
+            debug('ezs:info')(`Ignore item #${this.getIndex()} [URLStream]`, ezs.serializeError(e));
             return feed.send(data);
         }
-        debug('ezs')(`Break item #${this.getIndex()} [URLStream] <${e}>`);
+        debug('ezs:warn')(`Break item #${this.getIndex()} [URLStream]`, ezs.serializeError(e));
         return feed.send(e);
     };
     try {
diff --git a/packages/basics/test/basics.js b/packages/basics/test/basics.js
index b4adcbf74..8ac171139 100644
--- a/packages/basics/test/basics.js
+++ b/packages/basics/test/basics.js
@@ -115,7 +115,6 @@ describe('test', () => {
                 res.push(chunk);
             })
             .on('end', () => {
-                console.log(res);
                 assert.equal(3, res.length);
                 assert.equal('"a";"b";"c"\r\n', res[0]);
                 assert.equal('"1";"2";"3"\r\n', res[1]);
diff --git a/packages/basics/test/url-fetch.js b/packages/basics/test/url-fetch.js
index b7809ff55..6cd6ea4e0 100644
--- a/packages/basics/test/url-fetch.js
+++ b/packages/basics/test/url-fetch.js
@@ -43,6 +43,10 @@ httpbin
     .post('/status/400')
     .reply(400);
 
+httpbin
+    .get('/status/400')
+    .reply(400);
+
 httpbin
     .post('/status/503')
     .reply(503);
diff --git a/packages/conditor/src/corhal-fetch.js b/packages/conditor/src/corhal-fetch.js
index e1e7842eb..4a5ef59bb 100644
--- a/packages/conditor/src/corhal-fetch.js
+++ b/packages/conditor/src/corhal-fetch.js
@@ -78,7 +78,7 @@ export default async function CORHALFetch(data, feed) {
     };
     const onError = (e) => {
         controller.abort();
-        debug('ezs')(`Break item #${this.getIndex()} [CORHALFetch] <${e}>`);
+        debug('ezs:warn')(`Break item #${this.getIndex()} [CORHALFetch]`, ezs.serializeError(e));
         return feed.stop(e);
     };
     const loop = async (stream, arr, afterKeyToken) => {
@@ -102,7 +102,7 @@ export default async function CORHALFetch(data, feed) {
                 const { headers: headersBis, body: noticesBis } = await responseBis.json();
                 loop(stream, noticesBis, headersBis['after-key-token']);
             } catch (e) {
-                console.error(`Error with ${url}/after/`, e.message, e.body);
+                debug('ezs:error')(`Error with ${url}/after/`, ezs.serializeError(e));
                 stream.end();
             }
         } else {
diff --git a/packages/conditor/src/wos-fetch.js b/packages/conditor/src/wos-fetch.js
index 630a3f7b2..e3d497188 100644
--- a/packages/conditor/src/wos-fetch.js
+++ b/packages/conditor/src/wos-fetch.js
@@ -9,7 +9,7 @@ import writeTo from 'stream-write';
 import each from 'async-each-series';
 
 const request = (url, parameters) => async (bail, attempt) => {
-    debug('ezs')(`Request #${attempt} to ${url}`);
+    debug('ezs:debug')(`Request #${attempt} to ${url}`);
     const response = await fetch(url, parameters);
     if (!response.ok) {
         const { message } = await response.json();
@@ -87,7 +87,7 @@ export default async function WOSFetch(data, feed) {
     };
     const onError = (e) => {
         controller.abort();
-        debug('ezs')(`Break item #${this.getIndex()} [WOSFetch] <${e}>`);
+        debug('ezs:warn')(`Break item #${this.getIndex()} [WOSFetch]`, ezs.serializeError(e));
         return feed.stop(e);
     };
     const loop = async (stream, Records, reqPerSec, amtPerYear, QueryID, RecordsFound) => {
@@ -98,7 +98,7 @@ export default async function WOSFetch(data, feed) {
             try {
                 await write(stream, Records);
             } catch (e) {
-                console.error('Write Error', e.message);
+                debug('ezs:error')('Write Error', ezs.serializeError(e));
                 throw new Error(e);
             }
         }
@@ -127,7 +127,7 @@ export default async function WOSFetch(data, feed) {
             }
             await loop(stream, RecordsBis, reqPerSec, amtPerYear, QueryID, RecordsFound);
         } catch (e) {
-            console.error(`Error with ${cURLBis.href}`, e.message);
+            debug('ezs:error')(`Error with ${cURLBis.href}`, ezs.serializeError(e));
             throw new Error(e);
         }
     };
@@ -139,7 +139,7 @@ export default async function WOSFetch(data, feed) {
         const amtPerYear = response.headers.get('x-rec-amtperyear-remaining');
         const QueryID = get(jsonResponse, 'QueryResult.QueryID');
         const RecordsFound = get(jsonResponse, 'QueryResult.RecordsFound');
-        debug('ezs')(`Query #${QueryID} should download ${RecordsFound} notices (Allowed downloads remaining : ${amtPerYear})`);
+        debug('ezs:debug')(`Query #${QueryID} should download ${RecordsFound} notices (Allowed downloads remaining : ${amtPerYear})`);
         await loop(output, [], reqPerSec, amtPerYear, QueryID, RecordsFound);
         await feed.flow(output);
     } catch (e) {
diff --git a/packages/core/src/cli.js b/packages/core/src/cli.js
index 72902cdd8..9b5bcd80e 100644
--- a/packages/core/src/cli.js
+++ b/packages/core/src/cli.js
@@ -5,19 +5,25 @@ import yargs from 'yargs';
 import debug from 'debug';
 import ezs from '.';
 import File from './file';
-import { version } from '../package.json';
+import { VERSION, VERBOSE } from './constants';
 import settings from './settings';
 
 export default function cli(errlog) {
     const args = yargs
         .env('EZS')
         .usage('Usage: $0 [options] [<file>|<directory>] [<file2> <file3> ...]')
-        .version(version)
+        .version(VERSION)
         .options({
             verbose: {
                 alias: 'v',
                 default: false,
-                describe: 'Enable debug mode with DEBUG=ezs',
+                describe: `Make ezs more talkative, which is equivalent to setting the envar to DEBUG=${VERBOSE}`,
+                type: 'boolean',
+            },
+            logs: {
+                alias: 'l',
+                default: false,
+                describe: `Enable logs mode, which is equivalent to setting the envar to DEBUG_COLORS=0 DEBUG=${VERBOSE}`,
                 type: 'boolean',
             },
             tracer: {
@@ -66,7 +72,11 @@ export default function cli(errlog) {
     const { argv } = args;
 
     if (argv.verbose) {
-        debug.enable('ezs');
+        debug.enable(VERBOSE);
+    }
+    if (argv.logs) {
+        process.env.DEBUG_COLORS = 0;
+        debug.enable(VERBOSE);
     }
     if (argv.tracer) {
         settings.tracerEnable = true;
@@ -85,7 +95,7 @@ export default function cli(errlog) {
             errlog(`Error: ${argv.daemon} doesn't exists.`);
             process.exit(1);
         }
-        debug('ezs')(`Serving ${serverPath} with ${settings.concurrency} shards`);
+        debug('ezs:debug')(`Serving ${serverPath} with ${settings.concurrency} shards`);
         return ezs.createCluster(settings.port, serverPath);
     }
     if (argv._.length === 0) {
@@ -95,21 +105,21 @@ export default function cli(errlog) {
 
     let input;
     if (argv.env) {
-        debug('ezs')('Reading environment variables...');
+        debug('ezs:info')('Reading environment variables...');
         input = new PassThrough(ezs.objectMode());
         input.write(process.env);
         input.end();
     } else if (argv.file) {
         try {
             const filename = realpathSync(argv.file);
-            debug('ezs')(`Reading file ${filename} ...`);
+            debug('ezs:info')(`Reading file ${filename} ...`);
             input = createReadStream(filename);
         } catch (e) {
             errlog(`Error: ${argv.file} doesn't exists.`);
             process.exit(1);
         }
     } else {
-        debug('ezs')('Reading standard input...');
+        debug('ezs:info')('Reading standard input...');
         input = process.stdin;
         input.resume();
     }
diff --git a/packages/core/src/client.js b/packages/core/src/client.js
index 40783d48d..aedaaf918 100644
--- a/packages/core/src/client.js
+++ b/packages/core/src/client.js
@@ -66,7 +66,7 @@ export const connectServer = (ezs) => (serverOptions, index) => {
     const output = new PassThrough(ezs.objectMode());
     const handle = http.request(serverOptions, (res) => {
         connected = true;
-        debug('ezs')(`http://${hostname}:${port} send code ${res.statusCode}`);
+        debug('ezs:info')(`http://${hostname}:${port} send code ${res.statusCode}`);
         if (res.statusCode === 200) {
             res
                 .pipe(ezs.uncompress(res.headers))
@@ -94,7 +94,7 @@ export const connectServer = (ezs) => (serverOptions, index) => {
             ));
             return output.end();
         }
-        debug('ezs')(`http://${hostname}:${port} was stopped properly following ${e}`);
+        debug('ezs:info')(`http://${hostname}:${port} was stopped properly following`, ezs.serializeError(e));
         return 4;
     });
     handle.setNoDelay(false);
diff --git a/packages/core/src/compactor.js b/packages/core/src/compactor.js
index 3a3638e9b..9e4bfbd79 100644
--- a/packages/core/src/compactor.js
+++ b/packages/core/src/compactor.js
@@ -23,19 +23,19 @@ const z = chooseZ();
 export function compressStream(ezs, opts = {}) {
     const encoding = opts['Content-Encoding'] || opts['content-encoding'] || 'identity';
     if (typeof z.createGunzip === 'function' && encoding === 'gzip') {
-        debug('ezs')('ezs will use zlib to compress stream.');
+        debug('ezs:debug')('ezs will use zlib to compress stream.');
         return z.createGzip();
     }
-    debug('ezs')('ezs will not compress stream.');
+    debug('ezs:debug')('ezs will not compress stream.');
     return new PassThrough(ezs.bytesMode());
 }
 
 export function uncompressStream(ezs, opts = {}) {
     const encoding = opts['Content-Encoding'] || opts['content-encoding'] || 'identity';
     if (typeof z.createGunzip === 'function' && encoding === 'gzip') {
-        debug('ezs')('ezs will use zlib to uncompress stream.');
+        debug('ezs:debug')('ezs will use zlib to uncompress stream.');
         return z.createGunzip();
     }
-    debug('ezs')('ezs will not uncompress stream.');
+    debug('ezs:debug')('ezs will not uncompress stream.');
     return new PassThrough(ezs.bytesMode());
 }
diff --git a/packages/core/src/constants.js b/packages/core/src/constants.js
index 4dd34e1af..831a92dbf 100644
--- a/packages/core/src/constants.js
+++ b/packages/core/src/constants.js
@@ -1,6 +1,7 @@
 import filenameRegex from 'filename-regex';
 import { version } from '../package.json';
 
+export const VERBOSE = 'ezs:*,-ezs:debug,-ezs:trace';
 export const VERSION = version;
 export const STARTED_AT = Date.now();
 export const RX_FILENAME = filenameRegex();
diff --git a/packages/core/src/engine.js b/packages/core/src/engine.js
index f6decef39..099c47f90 100644
--- a/packages/core/src/engine.js
+++ b/packages/core/src/engine.js
@@ -51,17 +51,14 @@ function createErrorWith(error, index, funcName, funcParams, chunk) {
     const err = Error(msg);
     err.sourceError = error;
     err.sourceChunk = stringify(chunk);
-    err.toJSON = () => ({
-        type: error.type || 'Standard error',
-        scope: error.scope || 'code',
-        date: error.date || new Date(),
-        message: msg.split('\n').shift(),
-        func: funcName,
-        params: funcParams,
-        traceback: stk.slice(0,10),
-        index,
-        chunk,
-    });
+    err.type = error.type || 'Standard error';
+    err.scope = error.scope || 'code';
+    err.date = error.date || new Date();
+    err.message = msg.split('\n').shift();
+    err.func = funcName;
+    err.params = funcParams;
+    err.traceback = stk.slice(0,10);
+    err.index = index;
     Error.captureStackTrace(err, createErrorWith);
     return err;
 }
@@ -115,7 +112,7 @@ export default class Engine extends SafeTransform {
     _transform(chunk, encoding, done) {
         const start = hrtime.bigint();
         const next = () => {
-            if (debug.enabled('ezs')) {
+            if (debug.enabled('ezs:trace')) {
                 this.ttime += (hrtime.bigint() - start);
             }
             done();
@@ -141,10 +138,10 @@ export default class Engine extends SafeTransform {
         this.index += 1;
         return this.queue(null, () => {
             const stop = hrtime.bigint();
-            if (debug.enabled('ezs')) {
+            if (debug.enabled('ezs:trace')) {
                 const cumulative = nano2sec(stop - this.stime);
                 const elapsed = nano2sec(this.ttime);
-                debug('ezs')(`${cumulative}s cumulative ${elapsed}s elapsed for [${this.funcName}]`);
+                debug('ezs:trace')(`${cumulative}s cumulative ${elapsed}s elapsed for [${this.funcName}]`);
             }
             done();
         });
@@ -171,7 +168,7 @@ export default class Engine extends SafeTransform {
             if (!this.errorWasSent) {
               this.errorWasSent = true;
               const warnErr = createErrorWith(error, currentIndex, this.funcName, this.params, chunk);
-              debug('ezs')('ezs engine emit an', warnErr);
+              debug('ezs:warn')('ezs engine emit an', this.ezs.serializeError(warnErr));
               this.emit('error', warnErr);
             }
         };
@@ -180,7 +177,7 @@ export default class Engine extends SafeTransform {
                 this.nullWasSent = true;
                 this.nullWasSentError = createErrorWith(new Error('As a reminder, the end was recorded at this point'), currentIndex, this.funcName, this.params, chunk);
             } else if (this.nullWasSent && !this.errorWasSent) {
-                console.warn(createErrorWith(new Error('Oops, that\'s going to crash ?'), currentIndex, this.funcName, this.params, chunk));
+                debug('ezs:warn')('Unstable state', this.ezs.serializeError(createErrorWith(new Error('Oops, that\'s going to crash ?'), currentIndex, this.funcName, this.params, chunk)));
                 return warn(this.nullWasSentError);
             }
             if (!this.nullWasSent && this._readableState.ended) {
@@ -188,7 +185,7 @@ export default class Engine extends SafeTransform {
             }
             if (data instanceof Error) {
                 const ignoreErr = createErrorWith(data, currentIndex, this.funcName, this.params, chunk);
-                debug('ezs')(`Ignoring error at item #${currentIndex}`, ignoreErr);
+                debug('ezs:info')(`Ignoring error at item #${currentIndex}`, this.ezs.serializeError(ignoreErr));
                 return this.push(ignoreErr);
             }
             if (!this.errorWasSent) {
@@ -206,13 +203,13 @@ export default class Engine extends SafeTransform {
             this.chunk = chunk;
             return Promise.resolve(this.func.call(this.scope, chunk, feed, this.scope)).catch((e) => {
                 const asyncErr = createErrorWith(e, currentIndex, this.funcName, this.params, chunk);
-                debug('ezs')(`Async error thrown at item #${currentIndex}, pipeline is broken`, asyncErr);
+                debug('ezs:error')(`Async error thrown at item #${currentIndex}, pipeline is broken`, this.ezs.serializeError(asyncErr));
                 this.emit('error', asyncErr);
                 done();
             });
         } catch (e) {
             const syncErr = createErrorWith(e, currentIndex, this.funcName, this.params, chunk);
-            debug('ezs')(`Sync error thrown at item #${currentIndex}, pipeline carries errors`, syncErr);
+            debug('ezs:error')(`Sync error thrown at item #${currentIndex}, pipeline carries errors`, this.ezs.serializeError(syncErr));
             this.push(syncErr);
             return done();
         }
diff --git a/packages/core/src/feed.js b/packages/core/src/feed.js
index 4394cd84c..d5bbcfd4d 100644
--- a/packages/core/src/feed.js
+++ b/packages/core/src/feed.js
@@ -1,4 +1,5 @@
 import once from 'once';
+import debug from 'debug';
 import retimer from 'retimer';
 
 export default class Feed {
@@ -85,7 +86,7 @@ export default class Feed {
         return new Promise((resolve) => { this.log('Feed.flow.stream.end'); stream.once('end', resolve);});
     }
     log(x) {
-        //console.log(this.engine.funcName, x);
+        debug('ezs:debug')(this.engine.funcName, x);
     }
 
     end() {
diff --git a/packages/core/src/file.js b/packages/core/src/file.js
index 3dc1ee873..7fa553483 100644
--- a/packages/core/src/file.js
+++ b/packages/core/src/file.js
@@ -30,8 +30,8 @@ export function useFile(ezs, name) {
     if (plugName2) {
         return plugName2;
     }
-    debug('ezs')(`Unable to find '${name}' from ${plugName1}`);
-    debug('ezs')(`Unable to find '${name}' from ${plugName2}`);
+    debug('ezs:debug')(`Unable to find '${name}' from ${plugName1}`);
+    debug('ezs:debug')(`Unable to find '${name}' from ${plugName2}`);
     return false;
 }
 
@@ -39,7 +39,7 @@ export function isFile(file) {
     try {
         return statSync(file).isFile();
     } catch (e) {
-        debug('ezs')(`Unable to check '${file}'`);
+        debug('ezs:debug')(`Unable to check '${file}'`);
         return false;
     }
 }
@@ -48,7 +48,7 @@ export default function File(ezs, name) {
     try {
         const filename = [findFileIn(ezs.getPath(), name), check(name)].filter(Boolean).shift();
         if (!filename) {
-            debug('ezs')(`Unable to find '${name}' from ${filename}`);
+            debug('ezs:warn')(`Unable to find '${name}' from ${filename}`);
             return false;
         }
         ezs.addPath(dirname(filename));
diff --git a/packages/core/src/index.js b/packages/core/src/index.js
index b7e1c6f39..f7be26feb 100644
--- a/packages/core/src/index.js
+++ b/packages/core/src/index.js
@@ -1,4 +1,5 @@
 import { PassThrough } from 'readable-stream';
+import debug from 'debug';
 import writeTo from 'stream-write';
 import globalModules from 'global-modules';
 import { resolve } from 'path';
@@ -22,6 +23,7 @@ const ezs = (name, options, environment) => new Engine(ezs, Statement.get(ezs, n
 const ezsPath = [resolve(__dirname, '../..'), process.cwd(), globalModules];
 const ezsCache = new LRU(settings.cache);
 
+ezs.serializeError = (err) => JSON.stringify(err, Object.getOwnPropertyNames(err).sort());
 ezs.memoize = (key, func) => {
     if (!key || !settings.cacheEnable) {
         return func();
@@ -114,11 +116,11 @@ ezs.createPipeline = (input, commands, trap) => {
     }
     return output
         .pipe(ezs.catch((e) => {
-            trap.write(e.toJSON()); // see engine.js createErrorWith
+            trap.write(JSON.parse(ezs.serializeError(e))); // see engine.js createErrorWith
             return false; // do not catch the error
         }))
         .once('error', (e) => {
-            trap.write(e.toJSON()); // see engine.js createErrorWith
+            trap.write(JSON.parse(ezs.serializeError(e))); // see engine.js createErrorWith
             trap.end();
         })
         .once('end', () => {
@@ -137,7 +139,7 @@ ezs.createTrap = (file, env) => {
     const input = ezs.createStream(ezs.objectMode());
     ezs.createPipeline(input, ezs.compileCommands(ezs.createCommands({ file }), env))
         .once('error', (e) => {
-            console.warn(`WARNING: the trap failed, ${file} stopped at ${e.message}`);
+            debug('ezs:warn')(`The trap failed, ${file} stopped`, ezs.serializeError(e));
         })
         .once('end', () => true)
         .on('data', () => true);
diff --git a/packages/core/src/server/errorHandler.js b/packages/core/src/server/errorHandler.js
index 41d934d16..6c806ea80 100644
--- a/packages/core/src/server/errorHandler.js
+++ b/packages/core/src/server/errorHandler.js
@@ -2,13 +2,14 @@ import debug from 'debug';
 import JSONB from 'json-buffer';
 import { httpRequestErrorTotal }  from './metrics';
 
-const errorHandler = (request, response) => (error, code = 400) => {
-    debug('ezs')('Server has caught an error', code, error);
+const errorHandler = (ezs, request, response) => (error, code = 400) => {
+    const stringError = ezs.serializeError(error);
+    debug('ezs:error')(`Server has caught an error #${code}`, stringError);
     httpRequestErrorTotal.labels(request.pathName).inc();
     if (response.headersSent) {
         return response.end();
     }
-    const bodyResponse = JSONB.stringify(error);
+    const bodyResponse = JSONB.stringify(JSON.parse(stringError));
     response.writeHead(code, {
         'Content-Type': 'application/json',
         'Content-Length': bodyResponse.length,
diff --git a/packages/core/src/server/index.js b/packages/core/src/server/index.js
index 3c37e7bb2..83307800b 100644
--- a/packages/core/src/server/index.js
+++ b/packages/core/src/server/index.js
@@ -36,11 +36,11 @@ function methodMatch(values) {
 
 const signals = ['SIGINT', 'SIGTERM'];
 
-function createServer(ezs, serverPort, serverPath, workerId) {
+function createServer(ezs, serverPort, serverPath, worker) {
     const app = connect();
     app.use( async (request, response, next) => {
         const stopTimer = httpRequestDurationMicroseconds.startTimer();
-        request.workerId = workerId;
+        request.workerId = worker?.id;
         request.catched = false;
         request.serverPath = serverPath;
         request.urlParsed = parse(request.url, true);
@@ -67,33 +67,38 @@ function createServer(ezs, serverPort, serverPath, workerId) {
     app.use((request, response, next) => {
         if (request.catched === false) {
             const error = new Error(`Unable to create middleware for ${request.method} ${request.pathName}`);
-            errorHandler(request, response)(error, 404);
+            errorHandler(ezs, request, response)(error, 404);
         }
         next();
     });
     app.use((error, request, response, next) => {
-        errorHandler(request, response)(error, 400);
+        errorHandler(ezs, request, response)(error, 400);
         next();
     });
     const server = controlServer(http.createServer(app));
+    server.addListener('error', (error) => {
+        debug('ezs:error')(`Server with PID ${process.pid} fails`, ezs.serializeError(error));
+        worker.kill();
+    });
     server.setTimeout(0); // default value, useful?
     server.requestTimeout = 0; // ezs has its own timeout see feed.timeout
     server.listen(serverPort);
+
     server.addListener('connection', (socket) => {
         httpConnectionTotal.inc();
         httpConnectionOpen.inc();
         socket.on('error', (e) => {
-            debug('ezs')('Connection error, the server has stopped the request :', e.message);
+            debug('ezs:error')('Connection error, the server has stopped the request', ezs.serializeError(e));
         });
         socket.on('close', () => {
             httpConnectionOpen.dec();
         });
     });
     signals.forEach((signal) => process.on(signal, () => {
-        debug('ezs')(`Signal received, stoping server with PID ${process.pid}`);
+        debug('ezs:info')(`Signal received, stoping server with PID ${process.pid}`);
         server.shutdown(() => process.exit(0));
     }));
-    debug('ezs')(`Server starting with PID ${process.pid} and listening on port ${serverPort}`);
+    debug('ezs:info')(`Server starting with PID ${process.pid} and listening on port ${serverPort}`);
     return server;
 }
 
@@ -104,8 +109,9 @@ function createCluster(ezs, serverPort, serverPath) {
         for (let i = 0; i < settings.concurrency; i += 1) {
             cluster.fork();
         }
-        cluster.on('exit', () => {
+        cluster.on('exit', (worker, code, signal) => {
             if (!term) {
+                debug('ezs:info')(`Server with PID ${worker.process.pid} died with code=${code} signal=${signal}. restarting...`);
                 cluster.fork();
             }
         });
@@ -124,7 +130,7 @@ function createCluster(ezs, serverPort, serverPath) {
                     res.end();
                 }
             })).listen(serverPort + 1);
-            debug('ezs')(`Cluster metrics server listening on port ${serverPort+1}`);
+            debug('ezs:info')(`Cluster metrics server listening on port ${serverPort+1}`);
         }
         signals.forEach((signal) => {
             process.on(signal, () => {
@@ -136,7 +142,7 @@ function createCluster(ezs, serverPort, serverPath) {
             });
         });
     } else {
-        createServer(ezs, serverPort, serverPath, cluster.worker.id);
+        createServer(ezs, serverPort, serverPath, cluster.worker);
     }
     return cluster;
 }
diff --git a/packages/core/src/server/knownPipeline.js b/packages/core/src/server/knownPipeline.js
index d62c86f20..bae125d66 100644
--- a/packages/core/src/server/knownPipeline.js
+++ b/packages/core/src/server/knownPipeline.js
@@ -34,8 +34,8 @@ const knownPipeline = (ezs) => (request, response, next) => {
     const { headers, fusible, method, pathName } = request;
     const { query } = request.urlParsed;
 
-    debug('ezs')(`Create middleware 'knownPipeline' for ${method} ${pathName}`);
-    const triggerError = errorHandler(request, response);
+    debug('ezs:info')(`Create middleware 'knownPipeline' for ${method} ${pathName}`);
+    const triggerError = errorHandler(ezs, request, response);
     const files = ezs.memoize(`knownPipeline>${pathName}`,
         () => pathName
             .slice(1)
@@ -46,7 +46,7 @@ const knownPipeline = (ezs) => (request, response, next) => {
         triggerError(new Error(`Cannot find ${pathName}`), 404);
         return false;
     }
-    debug('ezs')(
+    debug('ezs:debug')(
         `PID ${process.pid} will execute ${pathName} commands with ${sizeof(query)}B of global parameters`,
     );
 
diff --git a/packages/core/src/server/serverControl.js b/packages/core/src/server/serverControl.js
index 1e51eddd5..95f4b24e2 100644
--- a/packages/core/src/server/serverControl.js
+++ b/packages/core/src/server/serverControl.js
@@ -6,7 +6,7 @@ const serverInformation =  () => (request, response, next) => {
         return next();
     }
     request.catched = true;
-    debug('ezs')(`Create middleware 'serverControl' for ${request.method} ${request.pathName}`);
+    debug('ezs:info')(`Create middleware 'serverControl' for ${request.method} ${request.pathName}`);
     const input = [];
     return request
         .on('error', err => next(err))
diff --git a/packages/core/src/server/serverInformation.js b/packages/core/src/server/serverInformation.js
index abb275c66..0b43fb83c 100644
--- a/packages/core/src/server/serverInformation.js
+++ b/packages/core/src/server/serverInformation.js
@@ -54,7 +54,7 @@ const globalSwaggerPaths = {
 };
 
 
-const collectMetadata = async (dirPath, hostName) => {
+const collectMetadata = async (ezs, dirPath, hostName) => {
     const globalSwagger = {
         openapi: '3.0.0',
         info: {
@@ -171,7 +171,7 @@ const collectMetadata = async (dirPath, hostName) => {
         }
     }
     catch(e) {
-        debug('ezs')('Unable to load swagger.json', e);
+        debug('ezs:warn')('Unable to load swagger.json', ezs.serializeError(e));
         return globalSwagger;
     }
     return globalSwagger;
@@ -220,7 +220,7 @@ const collectPaths = async (ezs, dirPath) => {
 };
 
 const collectAll = async (ezs, request) => {
-    const infos = await collectMetadata(request.serverPath, request.headers.host);
+    const infos = await collectMetadata(ezs, request.serverPath, request.headers.host);
     const paths = await collectPaths(ezs, request.serverPath);
     return ({ infos, paths });
 };
@@ -230,7 +230,7 @@ const serverInformation =  (ezs) => (request, response, next) => {
         return next();
     }
     request.catched = true;
-    debug('ezs')(`Create middleware 'serverInformation' for ${request.method} ${request.pathName}`);
+    debug('ezs:info')(`Create middleware 'serverInformation' for ${request.method} ${request.pathName}`);
 
     return collectAll(ezs, request)
         .then(({ infos, paths }) => {
diff --git a/packages/core/src/server/unknownPipeline.js b/packages/core/src/server/unknownPipeline.js
index 6b00fe02a..9b2153ad9 100644
--- a/packages/core/src/server/unknownPipeline.js
+++ b/packages/core/src/server/unknownPipeline.js
@@ -9,7 +9,7 @@ const unknownPipeline = ezs => (request, response, next) => {
         return next();
     }
     request.catched = true;
-    debug('ezs')(`Create middleware 'unknownPipeline' for ${request.method} ${request.pathName}`);
+    debug('ezs:info')(`Create middleware 'unknownPipeline' for ${request.method} ${request.pathName}`);
 
     const { headers } = request;
     response.setHeader('Content-Encoding', headers['content-encoding'] || 'identity');
@@ -28,7 +28,7 @@ const unknownPipeline = ezs => (request, response, next) => {
             };
         })
         .reduce((prev, cur) => Object.assign(prev, cur), {});
-    debug('ezs')(
+    debug('ezs:debug')(
         `PID ${process.pid} will execute ${commands.length} commands with ${sizeof(environment)} of global parameters`,
     );
     request
@@ -36,7 +36,7 @@ const unknownPipeline = ezs => (request, response, next) => {
         .pipe(ezs('unpack'))
         .pipe(ezs('ungroup'))
         .pipe(ezs('delegate', { commands }, environment))
-        .pipe(ezs.catch(errorHandler(request, response)))
+        .pipe(ezs.catch(errorHandler(ezs, request, response)))
         .pipe(ezs((input, output) => {
             if (!response.headersSent) {
                 response.writeHead(200);
diff --git a/packages/core/src/statement.js b/packages/core/src/statement.js
index a7032ae35..8de017649 100644
--- a/packages/core/src/statement.js
+++ b/packages/core/src/statement.js
@@ -17,7 +17,7 @@ function load(ezs, name) {
     const after1 = Object.keys(pluginsList);
     const diff1 = after1.filter((item) => before1.indexOf(item) === -1);
     if (diff1.length > 0) {
-        debug('ezs')(`These statements are registered: ${diff1.join(',')}`);
+        debug('ezs:debug')(`These statements are registered: ${diff1.join(',')}`);
     }
 }
 
diff --git a/packages/core/src/statements/breaker.js b/packages/core/src/statements/breaker.js
index 8cf1267d1..e11f8ed8f 100644
--- a/packages/core/src/statements/breaker.js
+++ b/packages/core/src/statements/breaker.js
@@ -17,7 +17,7 @@ export default async function breaker(data, feed) {
     }
     const check = await checkFusible(this.fusible);
     if (!check) {
-        debug('ezs')(`Stream break, ${this.fusible} no longer active.`);
+        debug('ezs:info')(`Stream break, ${this.fusible} no longer active.`);
         return feed.close(data);
     }
     return feed.send(data);
diff --git a/packages/core/src/statements/combine.js b/packages/core/src/statements/combine.js
index dcf641fac..3a93e7ffa 100644
--- a/packages/core/src/statements/combine.js
+++ b/packages/core/src/statements/combine.js
@@ -112,7 +112,6 @@ export default async function combine(data, feed) {
                 makeDir.sync(this.cachePath);
             }
         }
-        debug('ezs')('[combine] with sub pipeline.');
         const primer = this.getParam('primer', 'n/a');
         const commands = ezs.createCommands({
             file: this.getParam('file'),
@@ -123,6 +122,7 @@ export default async function combine(data, feed) {
             append: this.getParam('append'),
         });
         this.databaseID = hashCoerce.hash({ primer, commands });
+        debug('ezs:debug')(`[combine] with sub pipeline #${this.databaseID}`);
         const input = ezs.createStream(ezs.objectMode());
         this.database = {};
         let stream;
diff --git a/packages/core/src/statements/debug.js b/packages/core/src/statements/debug.js
index 60c0ca640..250d8dce0 100644
--- a/packages/core/src/statements/debug.js
+++ b/packages/core/src/statements/debug.js
@@ -1,58 +1,30 @@
-import util from 'util';
 import debugGlobal from 'debug';
 import _ from 'lodash';
 
 /**
- * Take `Object`, print it (with its number), and throw the same object.
- *
- * with ezs debug enabled:
- * every object will be stringify for printed and all others ezs debug traces will be print
- *
- * with ezs debug disabled:
- * every objects will be inspected (indented and colorized) and print on stderr (error level) or stdout (log level)
- *
- * if ezs parameter is set, every object are not log (it's a global action)
+ * Take `Object`, print it (with its number index), and throw the same object.
  *
  * @name debug
- * @param {String} [level=error] console level : log or error or silent
+ * @param {String} [level=info] DEBUG ezs level (depends of DEBUG env variable)
  * @param {String} [text=valueOf] text before the dump
  * @param {String} [path] path of field to print
- * @param {Boolean} [ezs] enable or disable ezs global debug traces
+ * @param {Boolean} [namespaces=ezs:*,-ezs:debug,-ezs:trace] set DEBUG namespaces
  * @returns {Object}
  */
 export default function debug(data, feed) {
     if (this.isLast()) {
         return feed.send(data);
     }
-    const level = String(this.getParam('level', 'error'));
+    const levelRaw = String(this.getParam('level', 'info'));
+    const level = ['trace', 'debug', 'info', 'warn', 'error'].includes(levelRaw) ? levelRaw : 'info';
     const text = String(this.getParam('text', 'valueOf'));
     const path = this.getParam('path', []);
     const keys = Array.isArray(path) ? path : [path];
     const output = keys.length === 0 ? data : _.pick(data, keys);
-    const mode = this.getParam('ezs', null);
 
-    if (mode !== null) {
-        if (Boolean(mode) === true && debugGlobal.enabled('ezs') === false) {
-            debugGlobal.enable('ezs');
-        }
-        if (Boolean(mode) === false && debugGlobal.enabled('ezs') === true) {
-            debugGlobal.enable('-ezs');
-        }
-        return feed.send(data);
-    }
     const logTitle = text.concat('#').concat(this.getIndex()).concat(' ->');
-    if (debugGlobal.enabled('ezs')) {
-        if (mode === null) {
-            debugGlobal('ezs')(logTitle, JSON.stringify(output));
-        }
-        return feed.send(data);
-    }
-    // eslint-disable-next-line
-    const logFunc = console[level];
-    if (typeof logFunc === 'function') {
-        const logOpts = { showHidden: false, depth: 3, colors: true };
-        const logDetails = util.inspect(output, logOpts);
-        logFunc(logTitle, logDetails);
-    }
+    const debugPrefix = `ezs:${level}`;
+
+    debugGlobal(debugPrefix)(`${logTitle} %j`, output);
     return feed.send(data);
 }
diff --git a/packages/core/src/statements/dedupe.js b/packages/core/src/statements/dedupe.js
index 2ea0372c9..23bda54c1 100644
--- a/packages/core/src/statements/dedupe.js
+++ b/packages/core/src/statements/dedupe.js
@@ -1,4 +1,5 @@
 import _ from 'lodash';
+import debug from 'debug';
 /**
  * Take `Object`, and check that the object identifier has not already been used previously
  *
@@ -20,14 +21,14 @@ export default async function dedupe(data, feed) {
     }
     if (uri === check) {
         if (ignore) {
-            console.warn(`WARNING: ${path} field not exists, item #${this.getIndex()} was ignored` );
+            debug('ezs:warn')(`${path} field not exists, item #${this.getIndex()} was ignored` );
             return feed.end();
         }
         return feed.send(new Error(`${path} field not exists, enable to dedupe.`));
     }
     if (this.previousURI[uri] === true) {
         if (ignore) {
-            console.warn(`WARNING: ${uri} already exists, item #${this.getIndex()} was ignored` );
+            debug('ezs:warn')(`${uri} already exists, item #${this.getIndex()} was ignored` );
             return feed.end();
         }
         return feed.send(new Error(`Duplicate identifier: ${uri} already exists`));
diff --git a/packages/core/src/statements/delegate.js b/packages/core/src/statements/delegate.js
index 8f1778af6..34fbf771a 100644
--- a/packages/core/src/statements/delegate.js
+++ b/packages/core/src/statements/delegate.js
@@ -32,7 +32,7 @@ export default function delegate(data, feed) {
         this.whenFinish = feed.flow(output, { autoclose: true });
     }
     if (this.isLast()) {
-        debug('ezs')(`${this.getIndex()} chunks have been delegated`);
+        debug('ezs:debug')(`${this.getIndex()} chunks have been delegated`);
         this.whenFinish.finally(() => feed.close());
         return this.input.end();
     }
diff --git a/packages/core/src/statements/dispatch.js b/packages/core/src/statements/dispatch.js
index 25aa6eb85..7b5242d17 100644
--- a/packages/core/src/statements/dispatch.js
+++ b/packages/core/src/statements/dispatch.js
@@ -38,7 +38,7 @@ export default function dispatch(data, feed) {
         ) {
             return feed.stop(new Error('Invalid parmeter for [dispatch]'));
         }
-        debug('ezs')(`[dispatch] connect to #${servers.length} servers.`);
+        debug('ezs:debug')(`[dispatch] connect to #${servers.length} servers.`);
         const handles = servers.map(connectServer(ezs));
         this.ins = handles.map((h) => h[0]);
         this.outs = handles.map((h) => h[1]);
diff --git a/packages/core/src/statements/fork.js b/packages/core/src/statements/fork.js
index 81c86339e..44438cce2 100644
--- a/packages/core/src/statements/fork.js
+++ b/packages/core/src/statements/fork.js
@@ -84,7 +84,7 @@ export default async function fork(data, feed) {
         }
     }
     if (this.isLast()) {
-        debug('ezs')(`${this.getIndex()} chunks have been delegated`);
+        debug('ezs:debug')(`${this.getIndex()} chunks have been delegated`);
         this.input.end();
         if (standalone) {
             feed.close();
diff --git a/packages/core/src/statements/map.js b/packages/core/src/statements/map.js
index c2bdd023f..d1d9bf5dc 100644
--- a/packages/core/src/statements/map.js
+++ b/packages/core/src/statements/map.js
@@ -1,4 +1,5 @@
 import _ from 'lodash';
+import debug from 'debug';
 import from from 'from';
 
 /**
@@ -44,7 +45,7 @@ export default function map(data, feed) {
     return output
         .pipe(ezs.catch())
         .on('error', (error) => {
-            console.warn(`WARNING: map ignore a item (${error})`);
+            debug('ezs:warn')('Map ignore a item', ezs.serializeError(error));
             feed.send(error);
         })
         .on('data', (chunk) => {
diff --git a/packages/core/src/statements/parallel.js b/packages/core/src/statements/parallel.js
index 1a740ee67..ab623fa2d 100644
--- a/packages/core/src/statements/parallel.js
+++ b/packages/core/src/statements/parallel.js
@@ -36,7 +36,7 @@ export default function parallel(data, feed) {
         if (!commands || commands.length === 0) {
             return feed.stop(new Error('Invalid parmeter for [parallel]'));
         }
-        debug('ezs')(`[parallel] start with #${concurrency} workers.`);
+        debug('ezs:debug')(`[parallel] start with #${concurrency} workers.`);
         const logger = ezs.createTrap(this.getParam('logger'), this.getEnv());
         const handles = Array(concurrency).fill(true).map(duplexer(ezs, commands, environment, logger));
         this.ins = handles.map((h) => h[0]);
diff --git a/packages/core/src/statements/singleton.js b/packages/core/src/statements/singleton.js
index 26612a1b7..4b046ccd7 100644
--- a/packages/core/src/statements/singleton.js
+++ b/packages/core/src/statements/singleton.js
@@ -18,7 +18,7 @@ export default function singleton(data, feed) {
     }
     if (this.isFirst()) {
         const { ezs } = this;
-        debug('ezs')('[singleton] starting once with one object.');
+        debug('ezs:debug')('[singleton] starting once with one object.');
         const savedData = { ...data };
         let result = {};
         const input = ezs.createStream(ezs.objectMode());
diff --git a/packages/core/src/statements/swing.js b/packages/core/src/statements/swing.js
index 76c26d843..9b306e960 100644
--- a/packages/core/src/statements/swing.js
+++ b/packages/core/src/statements/swing.js
@@ -37,7 +37,7 @@ export default function swing(data, feed) {
         this.whenFinish = feed.flow(output);
     }
     if (this.isLast()) {
-        debug('ezs')(`${this.getIndex()} chunks have been delegated`);
+        debug('ezs:debug')(`${this.getIndex()} chunks have been delegated`);
         this.whenFinish.finally(() => feed.close());
         return this.input.end();
     }
diff --git a/packages/core/src/statements/unpack.js b/packages/core/src/statements/unpack.js
index bb7556f95..7ff515ad0 100644
--- a/packages/core/src/statements/unpack.js
+++ b/packages/core/src/statements/unpack.js
@@ -40,7 +40,7 @@ export default function unpack(data, feed) {
             const lineParsed = JSON.parse(line);
             return feed.write(lineParsed);
         } catch(e) {
-            debug('ezs')(`[unpack] Syntax error at #${this.getIndex()+1} with <line>${line}</line>`);
+            debug('ezs:warn')(`[unpack] Syntax error at #${this.getIndex()+1} with <line>${line}</line>`, this.ezs.serializeError(e));
             return feed.stop(e);
         }
     });
diff --git a/packages/core/test/expand.js b/packages/core/test/expand.js
index 530d159e1..1d2512286 100644
--- a/packages/core/test/expand.js
+++ b/packages/core/test/expand.js
@@ -1,4 +1,5 @@
 import fs from 'fs';
+import debug from 'debug';
 import from from 'from';
 import { PassThrough } from 'stream';
 import ezs from '../src';
@@ -513,7 +514,12 @@ test('with a buggy script', (done) => {
             output.push(chunk);
         })
         .on('error', (e) => {
-            expect(e.message).toEqual(expect.stringContaining('BADVAL is not defined'));
+            try {
+                expect(e.message).toEqual(expect.stringContaining('Lodash'));
+            }
+            catch (ee) {
+                done(ee);
+            }
             expect(output.length).toEqual(0);
             done();
         })
diff --git a/packages/core/test/ezs.js b/packages/core/test/ezs.js
index dff5199c2..11e13198d 100644
--- a/packages/core/test/ezs.js
+++ b/packages/core/test/ezs.js
@@ -1,6 +1,7 @@
 import assert from 'assert';
 import Dir from 'path';
 import from from 'from';
+import debug from 'debug';
 import fs from 'fs';
 import { Readable, PassThrough } from 'stream';
 import ezs from '../src';
@@ -54,40 +55,45 @@ describe('Build a pipeline', () => {
             });
     });
     it('with debug transformation', (done) => {
+        debug.enable('ezs:*');
+        const namespaces = debug.disable();
         let res = 0;
         const ten = new Decade();
+        const script = `
+          [replace]
+          path = a
+          value = z
+          path = b
+          value = self()
+          path = c
+          value = none
+          [debug]
+          path = a
+          path = b
+        `;
         ten
             .pipe(ezs((input, output) => {
                 output.send(input);
             }))
             .pipe(ezs('tracer'))
-            .pipe(ezs('debug', {
-                text: 'Debug message (ezs = true)',
-                ezs: true,
-            }))
             .pipe(ezs('debug', {
                 text: 'Debug message',
             }))
             .pipe(ezs('debug', {
-                text: 'Debug message (ezs = false)',
-                ezs: false,
-            }))
-            .pipe(ezs('debug', {
-                text: 'Debug message (level = log)',
+                text: 'Debug message (unexsiting level)',
                 level: 'log',
             }))
             .pipe(ezs('debug', {
-                text: 'Debug message (level = error)',
-            }))
-            .pipe(ezs('debug', {
-                text: 'Debug message (level = silent)',
-                level: 'silent',
+                text: 'Debug message (level = trace)',
+                level: 'trace',
             }))
+            .pipe(ezs('delegate', { script }))
             .on('data', (chunk) => {
-                res += chunk;
+                res += chunk.b;
             })
             .on('end', () => {
                 assert.strictEqual(res, 45);
+                debug.enable(namespaces);
                 done();
             });
     });
diff --git a/packages/core/test/overturn.js b/packages/core/test/overturn.js
index f81f89e3f..b94301734 100644
--- a/packages/core/test/overturn.js
+++ b/packages/core/test/overturn.js
@@ -205,8 +205,12 @@ test('with a buggy script', (done) => {
             output.push(chunk);
         })
         .on('error', (e) => {
-            expect(e.message).toEqual(expect.stringContaining('BADVAL is not defined'));
-            expect(output.length).toEqual(0);
+            try {
+                expect(e.message).toEqual(expect.stringContaining('Lodash'));
+                expect(output.length).toEqual(0);
+            } catch (ee) {
+                done(ee);
+            }
             done();
         })
         .on('end', () => {
diff --git a/packages/spawn/package.json b/packages/spawn/package.json
index c9cf389a2..fb08f73bb 100644
--- a/packages/spawn/package.json
+++ b/packages/spawn/package.json
@@ -5,6 +5,7 @@
   "author": "Nicolas Thouvenin <nthouvenin@gmail.com>",
   "bugs": "https://github.com/Inist-CNRS/ezs/issues",
   "dependencies": {
+    "debug": "4.3.3",
     "semver": "7.5.2",
     "stream-iterate": "1.2.0"
   },
diff --git a/packages/spawn/src/exec.js b/packages/spawn/src/exec.js
index b36fefeec..189aabca1 100644
--- a/packages/spawn/src/exec.js
+++ b/packages/spawn/src/exec.js
@@ -1,3 +1,4 @@
+import debug from 'debug';
 import pool from './pool';
 
 /**
@@ -38,6 +39,7 @@ export default async function exec(data, feed) {
 
     let handle;
     try {
+        debug('ezs:info')(`Startup pool for ${command} with ${concurrency} process`);
         handle = await pool.startup(concurrency, command, args);
         if (!this.resource) {
             this.input = ezs.createStream(ezs.objectMode());
diff --git a/packages/storage/src/load.js b/packages/storage/src/load.js
index a6be298a5..8fb72ff01 100644
--- a/packages/storage/src/load.js
+++ b/packages/storage/src/load.js
@@ -1,4 +1,5 @@
 import { get, set } from 'lodash';
+import debug from 'debug';
 import store from './store';
 
 /**
@@ -10,6 +11,7 @@ import store from './store';
  * @returns {String}
  */
 export default async function load(data, feed) {
+    const { ezs } = this;
     const location = this.getParam('location');
     const pathName = this.getParam('path', 'uri');
     const path = Array.isArray(pathName) ? pathName.shift() : pathName;
@@ -29,7 +31,7 @@ export default async function load(data, feed) {
             return feed.close();
         }
         if (!uri) {
-            console.warn(`WARNING: uri was empty, [load] item #${this.getIndex()} was ignored`);
+            debug('ezs:warn')(`uri was empty, [load] item #${this.getIndex()} was ignored`);
             return feed.send(data);
         }
         const value = await this.store.get(uri);
@@ -40,7 +42,7 @@ export default async function load(data, feed) {
         return feed.send(value);
     } catch(e) {
         if (e.code === 'ENOENT') {
-            console.warn(`WARNING: uri not found (${uri}), item #${this.getIndex()} was ignored`, e);
+            debug('ezs:warn')(`uri not found (${uri}), item #${this.getIndex()} was ignored`, ezs.serializeError(e));
             if (target) {
                 set(data, target, undefined);
                 return feed.send(data);
diff --git a/packages/storage/src/save.js b/packages/storage/src/save.js
index 77427ee3b..59ff61a3b 100644
--- a/packages/storage/src/save.js
+++ b/packages/storage/src/save.js
@@ -1,4 +1,5 @@
 import { get } from 'lodash';
+import debug from 'debug';
 import store from './store';
 
 /**
@@ -33,7 +34,7 @@ export default async function save(data, feed) {
             await this.store.reset();
         }
         if (!uri) {
-            console.warn(`WARNING: uri was empty, [save] item #${this.getIndex()} was ignored`);
+            debug('ezs:warn')(`uri was empty, [save] item #${this.getIndex()} was ignored`);
             return feed.send(data);
         }
         await this.store.put(uri, data, score);
diff --git a/packages/store/src/store.js b/packages/store/src/store.js
index 58f519254..8979e2071 100644
--- a/packages/store/src/store.js
+++ b/packages/store/src/store.js
@@ -37,7 +37,7 @@ class Store {
             this.created = true;
             makeDir.sync(this.directory);
         }
-        debug('ezs')(`DB from ${this.directory}`, (this.created ? 'was created' : 'already exists'));
+        debug('ezs:info')(`DB from ${this.directory}`, (this.created ? 'was created' : 'already exists'));
         this.ready = new Promise((resolve, reject) => {
             if (!handle[this.directory]) {
                 levelup(leveldown(this.directory), {}, (err, db) => {
@@ -97,14 +97,14 @@ class Store {
                 return db.get(key2, (err1, value) => {
                     if (err1) {
                         if (err1.notFound) {
-                            console.error('WARNING', err1);
+                            debug('ezs:warn')('Not Found', this.ezs.serializeError(err1));
                             return resolve(null);
                         }
                         return reject(err1);
                     }
                     return db.del(key2, (err2) => {
                         if (err2) {
-                            console.error('WARNING', err2);
+                            debug('ezs:warn')('Unable to delete', this.ezs.serializeError(err2));
                         }
                         return resolve(decodeValue(value));
                     });
@@ -208,10 +208,10 @@ class Store {
 
     async close() {
         const db = await this.connect();
-        debug('ezs')(`DB from ${this.directory} is closing`);
+        debug('ezs:info')(`DB from ${this.directory} is closing`);
         delete handle[this.directory];
         if (!this.persistent) {
-            debug('ezs')(`DB from ${this.directory} is clearing`);
+            debug('ezs:info')(`DB from ${this.directory} is clearing`);
             await db.clear();
             await db.close();
             await del([this.directory], { force: true });
diff --git a/packages/transformers/src/operations/PARSE.js b/packages/transformers/src/operations/PARSE.js
index 656ef1574..1525b3a57 100644
--- a/packages/transformers/src/operations/PARSE.js
+++ b/packages/transformers/src/operations/PARSE.js
@@ -7,7 +7,6 @@ export const parse = value => {
     try {
         return JSON.parse(value);
     } catch (e) {
-        console.error(e);
         return value;
     }
 };