diff --git a/CHANGELOG b/CHANGELOG
index 0702f5d..d437885 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+v10.1.1:
+  date: 2024-07-18
+  changes:
+    - Fix formatting of non-string errors from `QUnit.on('error')` events.
 v10.1.0:
   date: 2024-07-18
   changes:
diff --git a/Gruntfile.js b/Gruntfile.js
index c972735..683ea90 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -110,6 +110,12 @@ module.exports = function(grunt) {
               /Chrome timed out/.test(stdout)) {
             cb(err !== null);
 
+          // qunit:failOnError
+          } else if (/test\/qunit_on_error\.html/.test(stdout) &&
+            stdout.includes('>> Error: boom') &&
+            /at .*qunit_on_error.html:15/.test(stdout)) {
+            cb(err !== null);
+
           // qunit:failPageError
           } else if (/test\/qunit_page_error\.html/.test(stdout) &&
               /ReferenceError: boom is not defined/.test(stdout) &&
@@ -146,6 +152,9 @@ module.exports = function(grunt) {
       failCircularObject: {
         command: 'grunt qunit:failCircularObject --with-failing'
       },
+      failOnError: {
+        command: 'grunt qunit:failOnError --with-failing'
+      },
       failPageError: {
         command: 'grunt qunit:failPageError --with-failing'
       },
@@ -179,6 +188,13 @@ module.exports = function(grunt) {
         ]
       }
     });
+    grunt.config.set('qunit.failOnError', {
+      options: {
+        urls: [
+          'http://localhost:9000/test/qunit_on_error.html'
+        ]
+      }
+    });
     grunt.config.set('qunit.failPageError', {
       options: {
         urls: [
diff --git a/README.md b/README.md
index 661da59..29d726f 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# grunt-contrib-qunit v10.1.0 [![Build Status](https://github.com/gruntjs/grunt-contrib-qunit/workflows/Tests/badge.svg)](https://github.com/gruntjs/grunt-contrib-qunit/actions?workflow=Tests)
+# grunt-contrib-qunit v10.1.1 [![Build Status](https://github.com/gruntjs/grunt-contrib-qunit/workflows/Tests/badge.svg)](https://github.com/gruntjs/grunt-contrib-qunit/actions?workflow=Tests)
 
 > Run QUnit unit tests in a headless Chrome instance
 
@@ -272,6 +272,7 @@ grunt.event.on('qunit.on.testEnd', function (test) {
 
 ## Release History
 
+ * 2024-07-18   v10.1.1   Fix formatting of non-string errors from `QUnit.on('error')` events.
  * 2024-07-18   v10.1.0   Include errors from `QUnit.on('error')` in the output.
  * 2024-06-18   v10.0.0   Remove support for delaying qunit.js via RequireJS. AMD continues to be supported for loading source code and tests, but load qunit.js in its own script before RequireJS, and reference QUnit directly. Examples on [qunitjs.com](https://qunitjs.com/api/config/autostart/).
  * 2024-06-11   v9.1.1   Remove dependency on `p-each-series` package.
diff --git a/chrome/bridge.js b/chrome/bridge.js
index 9f78336..c9f41f6 100644
--- a/chrome/bridge.js
+++ b/chrome/bridge.js
@@ -41,7 +41,7 @@
   // https://qunitjs.com/api/callbacks/QUnit.on/
 
   QUnit.on('error', function(error) {
-    sendMessage('qunit.on.error', error);
+    sendMessage('qunit.on.error', error.stack || String(error));
   });
 
   QUnit.on('testStart', function(obj) {
diff --git a/package-lock.json b/package-lock.json
index f3023db..1cf6a4d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "grunt-contrib-qunit",
-  "version": "10.1.0",
+  "version": "10.1.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "grunt-contrib-qunit",
-      "version": "10.1.0",
+      "version": "10.1.1",
       "license": "MIT",
       "dependencies": {
         "eventemitter2": "^6.4.9",
diff --git a/package.json b/package.json
index 83ac85a..6682c21 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "grunt-contrib-qunit",
   "description": "Run QUnit unit tests in a headless Chrome instance",
-  "version": "10.1.0",
+  "version": "10.1.1",
   "author": {
     "name": "Grunt Team",
     "url": "https://gruntjs.com/"
diff --git a/tasks/qunit.js b/tasks/qunit.js
index ddc5dbf..f075ef7 100644
--- a/tasks/qunit.js
+++ b/tasks/qunit.js
@@ -246,7 +246,7 @@ module.exports = function(grunt) {
     // by QUnit plugins.
     // https://qunitjs.com/api/extension/QUnit.onUncaughtException/
     grunt.log.writeln();
-    grunt.log.error(err.stack || err);
+    grunt.log.error(err);
     grunt.event.emit('qunit.error.onError', err);
   });
 
diff --git a/test/qunit_on_error.html b/test/qunit_on_error.html
new file mode 100644
index 0000000..dc03018
--- /dev/null
+++ b/test/qunit_on_error.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test Suite</title>
+  <link rel="stylesheet" href="../node_modules/qunit/qunit/qunit.css" media="screen">
+  <script src="../node_modules/qunit/qunit/qunit.js"></script>
+</head>
+<body>
+  <div id="qunit"></div>
+  <div id="qunit-fixture"></div>
+  <script>
+    QUnit.moduleStart(function () {
+      try {
+        throw new Error('boom');
+      } catch (e) {
+        QUnit.onUncaughtException(e);
+      }
+    });
+    QUnit.test('basic test', function(assert) {
+      assert.ok(true);
+    });
+  </script>
+</body>
+</html>