diff --git a/src/gmv/blowfish.py b/src/gmv/blowfish.py
index 34602089..b6f058bf 100644
--- a/src/gmv/blowfish.py
+++ b/src/gmv/blowfish.py
@@ -59,7 +59,7 @@ class Blowfish:
     DECRYPT = 1
  
     # For _round()
-    _MODULUS = 2L ** 32
+    _MODULUS = 2 ** 32
  
     # CTR constants
     _BLOCK_SIZE = 8
@@ -528,23 +528,23 @@ def _round(self, xl):
  
     def _demo(heading, source, encrypted, decrypted):
         """demo method """
-        print heading
-        print "\tSource: %(source)s" % {
+        print(heading)
+        print("\tSource: %(source)s" % {
          'source': source,
-        }
-        print "\tEncrypted: %(encrypted)s" % {
+        })
+        print("\tEncrypted: %(encrypted)s" % {
          'encrypted': encrypted,
-        }
-        print "\tDecrypted: %(decrypted)s" % {
+        })
+        print("\tDecrypted: %(decrypted)s" % {
          'decrypted': decrypted,
-        }
-        print
+        })
+        print()
  
     key = 'This is a test key'
     cipher = Blowfish(key)
  
     # Encryption processing
-    (xl, xr) = (123456L, 654321L)
+    (xl, xr) = (123456, 654321)
     (cl, cr) = cipher.cipher(xl, xr, cipher.ENCRYPT)
     (dl, dr) = cipher.cipher(cl, cr, cipher.DECRYPT)
     _demo("Testing encryption", (xl, xr), (cl, cr), (dl, dr))
@@ -564,7 +564,7 @@ def _demo(heading, source, encrypted, decrypted):
     _demo("Testing CTR logic", text, repr(crypted), decrypted)
  
     # Test speed
-    print "Testing speed"
+    print("Testing speed")
     test_strings = [''.join(("The quick brown fox jumps over the lazy dog", str(i),)) for i in xrange(1000)]
     n = 0
     t1 = time.time()
@@ -575,8 +575,8 @@ def _demo(heading, source, encrypted, decrypted):
         t2 = time.time()
         if t2 - t1 >= 5.0:
             break
-    print "%(count)i encryptions in %(time)0.1f seconds: %(throughput)0.1f enc/s" % {
+    print("%(count)i encryptions in %(time)0.1f seconds: %(throughput)0.1f enc/s" % {
      'count': n,
      'time': t2 - t1,
      'throughput': n / (t2 - t1),
-    }
+    })
diff --git a/src/gmv/cmdline_utils.py b/src/gmv/cmdline_utils.py
index e195cd76..7050f06c 100755
--- a/src/gmv/cmdline_utils.py
+++ b/src/gmv/cmdline_utils.py
@@ -75,7 +75,7 @@ def print_help(self, out=sys.stderr):
         super(CmdLineParser, self).print_help(out)
         if self.epilogue: 
             #print >> out, '\n%s' % textwrap.fill(self.epilogue, 100, replace_whitespace = False) 
-            print >> out, '\n%s' % self.epilogue
+            print('\n%s' % self.epilogue, file=out)
             out.flush() 
    
     def show_usage(self, msg=None): 
@@ -97,7 +97,7 @@ def die_with_usage(self, msg=None, exit_code=2):
                   The process exit code. Defaults to 2. 
         """ 
         if msg != None: 
-            print >> sys.stderr, msg 
+            print(msg, file=sys.stderr)
         
         self.print_help(sys.stderr) 
         sys.exit(exit_code) 
diff --git a/src/gmv/conf/conf_helper.py b/src/gmv/conf/conf_helper.py
index 7efc79a2..621fbfe3 100755
--- a/src/gmv/conf/conf_helper.py
+++ b/src/gmv/conf/conf_helper.py
@@ -101,10 +101,10 @@ def _get_value_from_command_line(self):
         for arg in sys.argv:
             if arg.lower() == the_s:
                 i = sys.argv.index(arg)
-                #print "i = %d, val = %s\n"%(i,sys.argv[i])
+                #print("i = %d, val = %s\n"%(i,sys.argv[i]))
                 if len(sys.argv) <= i:
                     # No more thing to read in the command line so quit
-                    print "Resource: Commandline argument %s has no value\n" % (self._cli_arg)
+                    print("Resource: Commandline argument %s has no value\n" % (self._cli_arg))
                     return None 
                 else:
                     #print "i+1 = %d, val = %s\n"%(i+1,sys.argv[i+1])
@@ -243,7 +243,7 @@ def get_value_as_boolean(self):
         """
         val = self.get_value()
         if val.lower() not in self._boolean_states:
-            raise ValueError, 'Not a boolean: %s' % val
+            raise ValueError( 'Not a boolean: %s' % val)
         return self._boolean_states[val.lower()]
 
 class MockConf(object):
@@ -409,9 +409,9 @@ def _load_config(self, a_file=None):
             # memorize conf file path
             self._configuration_file_path = a_file
 
-        except Exception, exce:
-            print "Can't read the config file %s" % a_file
-            print "Current executing from dir = %s\n" % os.getcwd()
+        except Exception as exce:
+            print("Can't read the config file %s" % a_file)
+            print("Current executing from dir = %s\n" % os.getcwd())
             raise exce
 
     def get_conf_file_path(self):
@@ -639,7 +639,7 @@ def _replace_vars(self, a_str, location, lineno= - 1):
                         dummy = res.get_value()
                     else:
                         dummy = self._sections[group][self.optionxform(option)]
-                except KeyError, _: #IGNORE:W0612
+                except KeyError as _: #IGNORE:W0612
                     raise exceptions.SubstitutionError(lineno, location, "Property %s[%s] "\
                                                        "doesn't exist in this configuration file \n" \
                                                        % (group, option))
@@ -682,14 +682,14 @@ def getboolean(self, section, option, default=False, fail_if_missing=False):
         """getboolean value""" 
         val = self.get(section, option, default, fail_if_missing)
         if val.lower() not in self._boolean_states:
-            raise ValueError, 'Not a boolean: %s' % val
+            raise ValueError('Not a boolean: %s' % val)
         return self._boolean_states[val.lower()]
     
     def get_boolean(self, section, option, default=False, fail_if_missing=False):
         """get_boolean value"""
         val = self.get(section, option, default, fail_if_missing)
         if val.lower() not in self._boolean_states:
-            raise ValueError, 'Not a boolean: %s' % val
+            raise ValueError('Not a boolean: %s' % val)
         return self._boolean_states[val.lower()]
     
     def get_list(self, section, option, default=None, fail_if_missing=False):
@@ -701,7 +701,7 @@ def get_list(self, section, option, default=None, fail_if_missing=False):
         try:
             compiler = struct_parser.Compiler()
             return compiler.compile_list(val)
-        except struct_parser.CompilerError, err: 
+        except struct_parser.CompilerError as err: 
             raise exceptions.Error(err.message)
     
     def getlist(self, section, option, default=None, fail_if_missing=False):
@@ -722,7 +722,7 @@ def get_dict(self, section, option, default=None, fail_if_missing=False):
         try:
             compiler = struct_parser.Compiler()
             return compiler.compile_dict(val)
-        except struct_parser.CompilerError, err: 
+        except struct_parser.CompilerError as err: 
             raise exceptions.Error(err.message)
         
     @classmethod
diff --git a/src/gmv/conf/conf_tests.py b/src/gmv/conf/conf_tests.py
index e932f231..a0e1cd02 100755
--- a/src/gmv/conf/conf_tests.py
+++ b/src/gmv/conf/conf_tests.py
@@ -265,7 +265,7 @@ def test_dict_error(self):
         
         try:
             self.conf.get_dict('GroupTestValueStruct', 'dict_error')
-        except Exception, err:
+        except Exception as err:
             self.assertEquals(err.message, "Expression \"{1:2,'v b': a\" cannot be converted as a dict.")
             return
         
@@ -277,7 +277,7 @@ def test_list_error(self):
         try:
             the_list = self.conf.get_list('GroupTestValueStruct', 'list_error')
             print('the_list = %s\n' % (the_list))
-        except Exception, err:
+        except Exception as err:
             self.assertEquals(err.message, 'Unsupported token (type: @, value : OP) (line=1,col=3).')
             return
          
diff --git a/src/gmv/conf/utils/struct_parser.py b/src/gmv/conf/utils/struct_parser.py
index 6b174147..641967ac 100755
--- a/src/gmv/conf/utils/struct_parser.py
+++ b/src/gmv/conf/utils/struct_parser.py
@@ -18,7 +18,10 @@
 '''
 import tokenize
 import token
-import StringIO
+try:
+    from StringIO import StringIO ## for Python 2
+except ImportError:
+    from io import StringIO ## for Python 3
 
 class TokenizerError(Exception):
     """Base class for All exceptions"""
@@ -109,7 +112,7 @@ def tokenize(self, a_program, a_eatable_token_types = ()):
             Raises:
                exception TokenizerError if the syntax of the aString string is incorrect
         """
-        g_info = tokenize.generate_tokens(StringIO.StringIO(a_program).readline)   # tokenize the string
+        g_info = tokenize.generate_tokens(StringIO(a_program).readline)   # tokenize the string
         
         for toknum, tokval, tokbeg, tokend, tokline  in g_info:
             if token.tok_name[toknum] not in a_eatable_token_types:
@@ -266,7 +269,7 @@ def compile_list(self, a_to_compile_str):
         try:
             tokenizer = Tokenizer()
             tokenizer.tokenize(a_to_compile_str, self._tokens_to_ignore)
-        except tokenize.TokenError, err:
+        except tokenize.TokenError as err:
             
             #translate this error into something understandable. 
             #It is because the bloody tokenizer counts the brackets
@@ -287,7 +290,7 @@ def compile_dict(self, a_to_compile_str):
         try:
             tokenizer = Tokenizer()
             tokenizer.tokenize(a_to_compile_str, self._tokens_to_ignore)
-        except tokenize.TokenError, err:
+        except tokenize.TokenError as err:
             
             #translate this error into something understandable. 
             #It is because the bloody tokenizer counts the brackets
@@ -423,8 +426,8 @@ def _compile_litteral(self, a_tokenizer):
                 #check if the string is unicode
                 if len(the_token.value) >= 3 and the_token.value[:2] == "u'":
                     #unicode string
-                    #dummy = unicode(the_token.value[2:-1], 'utf_8') #decode from utf-8 encoding not necessary if read full utf-8 file
-                    dummy = unicode(the_token.value[2:-1])
+                    #dummy = str(the_token.value[2:-1], 'utf_8') #decode from utf-8 encoding not necessary if read full utf-8 file
+                    dummy = str(the_token.value[2:-1])
                 else:
                     #ascii string
                     # the value contains the quote or double quotes so remove them always
diff --git a/src/gmv/conf/utils/struct_parser_tests.py b/src/gmv/conf/utils/struct_parser_tests.py
index 14144af7..c4ae51b1 100755
--- a/src/gmv/conf/utils/struct_parser_tests.py
+++ b/src/gmv/conf/utils/struct_parser_tests.py
@@ -89,7 +89,7 @@ def test_list_error(self):
         
         try:
             compiler.compile_list(the_string)
-        except CompilerError, err:
+        except CompilerError as err:
             self.assertEqual(err.message, 'Expression "  a ]" cannot be converted as a list.')
     
     def test_list_unicode_val(self):
@@ -126,7 +126,7 @@ def test_list_error_2(self):
         
         try:
             compiler.compile_list(the_string)
-        except CompilerError, err:
+        except CompilerError as err:
             self.assertEqual(err.message, 'Unsupported token (type: @, value : OP) (line=1,col=3).')
         
     def test_simple_dict(self):
@@ -148,7 +148,7 @@ def test_dict_error(self):
         
         try:
             compiler.compile_dict(the_string)
-        except CompilerError, err:
+        except CompilerError as err:
             self.assertEqual(err.message, 'Expression "{\'a\':1, b:2 " cannot be converted as a dict.')
         
     def test_dict_with_list(self):
diff --git a/src/gmv/credential_utils.py b/src/gmv/credential_utils.py
index dc08c7ed..b1a1257c 100755
--- a/src/gmv/credential_utils.py
+++ b/src/gmv/credential_utils.py
@@ -24,7 +24,7 @@
 import json
 import base64
 import urllib #for urlencode
-import urllib2
+import urllib.request #for urlencode
 
 import os
 import getpass
@@ -74,7 +74,7 @@ def get_secret_key(cls, a_filepath):
         else:
             secret = gmvault_utils.make_password()
 
-            fdesc = os.open(a_filepath, os.O_CREAT|os.O_WRONLY, 0600)
+            fdesc = os.open(a_filepath, os.O_CREAT|os.O_WRONLY, 0o600)
             try:
                 the_bytes = os.write(fdesc, secret)
             finally:
@@ -92,7 +92,7 @@ def store_passwd(cls, email, passwd):
         """
         passwd_file = '%s/%s.passwd' % (gmvault_utils.get_home_dir_path(), email)
     
-        fdesc = os.open(passwd_file, os.O_CREAT|os.O_WRONLY, 0600)
+        fdesc = os.open(passwd_file, os.O_CREAT|os.O_WRONLY, 0o600)
         
         cipher       = blowfish.Blowfish(cls.get_secret_key(cls.SECRET_FILEPATH % (gmvault_utils.get_home_dir_path())))
         cipher.initCTR()
@@ -153,7 +153,7 @@ def read_oauth2_tok_sec(cls, email):
             try:
                 with open(user_oauth_file_path) as oauth_file:
                     oauth_result = json.load(oauth_file)
-            except Exception, _: #pylint: disable-msg=W0703
+            except Exception as _: #pylint: disable-msg=W0703
                 LOG.critical("Cannot read oauth credentials from %s. Force oauth credentials renewal." % user_oauth_file_path)
                 LOG.critical("=== Exception traceback ===")
                 LOG.critical(gmvault_utils.get_exception_traceback())
@@ -261,8 +261,8 @@ def _get_oauth2_acc_tok_from_ref_tok(cls, refresh_token):
       request_url = '%s/%s' % (account_base_url, 'o/oauth2/token')
 
       try:
-        response = urllib2.urlopen(request_url, urllib.urlencode(params)).read()
-      except Exception, err: #pylint: disable-msg=W0703
+        response = urllib.request.urlopen(request_url, urllib.urlencode(params)).read()
+      except Exception as err: #pylint: disable-msg=W0703
         LOG.critical("Error: Problems when trying to connect to Google oauth2 endpoint: %s.\n" % (request_url))
         raise err
 
@@ -300,8 +300,8 @@ def _get_authorization_tokens(cls, authorization_code):
         request_url = '%s/%s' % (account_base_url, 'o/oauth2/token')
 
         try:
-            response = urllib2.urlopen(request_url, urllib.urlencode(params)).read()
-        except Exception, err: #pylint: disable-msg=W0703
+            response = urllib.request.urlopen(request_url, urllib.urlencode(params)).read()
+        except Exception as err: #pylint: disable-msg=W0703
             LOG.critical("Error: Problems when trying to connect to Google oauth2 endpoint: %s." % (request_url))
             raise err
 
@@ -325,7 +325,7 @@ def _get_oauth2_tokens(cls, email, use_webbrowser = False, debug=False):
         if use_webbrowser:
             try:
                 webbrowser.open(str(permission_url))
-            except Exception, err: #pylint: disable-msg=W0703
+            except Exception as err: #pylint: disable-msg=W0703
                 LOG.critical("Error: %s.\n" % (err) )
                 LOG.critical("=== Exception traceback ===")
                 LOG.critical(gmvault_utils.get_exception_traceback())
diff --git a/src/gmv/gmv_cmd.py b/src/gmv/gmv_cmd.py
index f245aada..46746752 100755
--- a/src/gmv/gmv_cmd.py
+++ b/src/gmv/gmv_cmd.py
@@ -456,7 +456,7 @@ def _parse_common_args(cls, options, parser, parsed_args, list_of_types = []): #
                 port = int(options.port)
             else:
                 port = options.port
-        except Exception, _: #pylint:disable=W0703
+        except Exception as _: #pylint:disable=W0703
             parser.error("--port option %s is not a number. Please check the port value" % (port))
             
         # add port
@@ -763,7 +763,7 @@ def run(self, args): #pylint:disable=R0912
             
             on_error = False
         
-        except KeyboardInterrupt, _:
+        except KeyboardInterrupt as _:
             LOG.critical("\nCTRL-C. Stop all operations.\n")
             on_error = False
         except socket.error:
@@ -773,7 +773,7 @@ def run(self, args): #pylint:disable=R0912
             LOG.critical(gmvault_utils.get_exception_traceback())
             LOG.critical("=== End of Exception traceback ===\n")
             die_with_usage = False
-        except imaplib.IMAP4.error, imap_err:
+        except imaplib.IMAP4.error as imap_err:
             #bad login or password
             if str(imap_err) in ['[AUTHENTICATIONFAILED] Invalid credentials (Failure)', \
                                  '[ALERT] Web login required: http://support.google.com/'\
@@ -787,7 +787,7 @@ def run(self, args): #pylint:disable=R0912
                 LOG.critical("=== Exception traceback ===")
                 LOG.critical(gmvault_utils.get_exception_traceback())
                 LOG.critical("=== End of Exception traceback ===\n")
-        except Exception, err:
+        except Exception as err:
             LOG.critical("Error: %s. \n" % (err) )
             LOG.critical("=== Exception traceback ===")
             LOG.critical(gmvault_utils.get_exception_traceback())
diff --git a/src/gmv/gmvault.py b/src/gmv/gmvault.py
index c127698e..2b55cfde 100755
--- a/src/gmv/gmvault.py
+++ b/src/gmv/gmvault.py
@@ -99,7 +99,7 @@ def handle_sync_imap_error(the_exception, the_id, error_report, src):
         try:
             #try to get the gmail_id
             curr = src.fetch(the_id, imap_utils.GIMAPFetcher.GET_GMAIL_ID) 
-        except Exception, _: #pylint:disable-msg=W0703
+        except Exception as _: #pylint:disable-msg=W0703
             curr = None
             LOG.critical("Error when trying to get gmail id for message with imap id %s." % (the_id))
             LOG.critical("Disconnect, wait for 10 sec then reconnect.")
@@ -135,7 +135,7 @@ def handle_sync_imap_error(the_exception, the_id, error_report, src):
                 #try to get the gmail_id
                 LOG.critical("One more attempt. Trying to fetch the Gmail ID for %s" % (the_id) )
                 curr = src.fetch(the_id, imap_utils.GIMAPFetcher.GET_GMAIL_ID) 
-            except Exception, _: #pylint:disable-msg=W0703
+            except Exception as _: #pylint:disable-msg=W0703
                 curr = None
             
             if curr:
@@ -179,7 +179,7 @@ def individual_fetch(self, imap_ids):
             try: 
                 single_data = self.src.fetch(the_id, self.request)
                 new_data.update(single_data)                
-            except Exception, error:
+            except Exception as error:
                 handle_sync_imap_error(error, the_id, self.error_report, self.src) #do everything in this handler
 
         return new_data
@@ -205,7 +205,7 @@ def next(self):
             
             return new_data
 
-        except imaplib.IMAP4.error, _:
+        except imaplib.IMAP4.error as _:
             new_data = self.individual_fetch(batch) 
     
         return new_data
@@ -331,7 +331,7 @@ def check_email_on_disk(cls, a_gstorer, a_id, a_dir = None):
             if a_dir:
                 return a_gstorer.unbury_metadata(a_id, a_dir) 
             
-        except ValueError, json_error:
+        except ValueError as json_error:
             LOG.exception("Cannot read file %s. Try to fetch the data again" % ('%s.meta' % (a_id)), json_error )
         
         return None
@@ -491,7 +491,7 @@ def _common_sync(self, a_timer, a_type, imap_req, compress, restart):
                     try:
                         new_data[the_id][imap_utils.GIMAPFetcher.GMAIL_LABELS] = \
                              imap_utils.decode_labels(new_data[the_id][imap_utils.GIMAPFetcher.GMAIL_LABELS])
-                    except KeyError, ke:
+                    except KeyError as ke:
                         LOG.info("KeyError, reason: %s. new_data[%s]=%s" % (str(ke), the_id, new_data.get(the_id)))
                         # try to fetch it individually and replace current info if it fails then raise error.
                         id_info = None
@@ -499,7 +499,7 @@ def _common_sync(self, a_timer, a_type, imap_req, compress, restart):
                             id_info = batch_fetcher.individual_fetch(the_id)
                             new_data[the_id][imap_utils.GIMAPFetcher.GMAIL_LABELS] = \
                                 imap_utils.decode_labels(id_info[imap_utils.GIMAPFetcher.GMAIL_LABELS])
-                        except Exception, err:
+                        except Exception as err:
                             LOG.debug("Error when trying to fetch again information for email id %s. id_info = %s. exception:(%s)" \
                                       % (the_id, id_info, str(err)))
                             LOG.info("Missing labels information for email id %s. Ignore it\n" % (the_id))
@@ -543,7 +543,7 @@ def _common_sync(self, a_timer, a_type, imap_req, compress, restart):
                             
                             #update local index id gid => index per directory to be thought out
                             LOG.debug("Create and store email with imap id %s, gmail id %s." % (the_id, gid))   
-                        except Exception, error:
+                        except Exception as error:
                             handle_sync_imap_error(error, the_id, self.error_report, self.src) #do everything in this handler    
                     
                     nb_msgs_processed += 1
@@ -731,7 +731,7 @@ def get_gmails_ids_left_to_sync(self, op_type, imap_ids, imap_req):#pylint:disab
             LOG.critical("Restart from gmail id %s (imap id %s)." % (last_id, imap_id))
             
             new_gmail_ids = imap_ids[last_id_index:]   
-        except Exception, _: #ignore any exception and try to get all ids in case of problems. pylint:disable=W0703
+        except Exception as _: #ignore any exception and try to get all ids in case of problems. pylint:disable=W0703
             #element not in keys return current set of keys
             LOG.critical("Error: Cannot restore from last restore gmail id. It is not in Gmail."\
                          " Sync the complete list of gmail ids requested from Gmail.")
@@ -866,7 +866,7 @@ def get_gmails_ids_left_to_restore(self, op_type, db_gmail_ids_info):
             keys = db_gmail_ids_info.keys()
             last_id_index = keys.index(last_id)
             LOG.critical("Restart from gmail id %s." % last_id)
-        except ValueError, _:
+        except ValueError as _:
             #element not in keys return current set of keys
             LOG.error("Cannot restore from last restore gmail id. It is not in the disk database.")
 
@@ -1000,7 +1000,7 @@ def restore_chats(self, extra_labels = [], restart = False): #pylint:disable=W01
                     for ex_label in extra_labels: 
                         labels_to_apply[ex_label] = imap_id
                 
-                except Exception, err:
+                except Exception as err:
                     handle_restore_imap_error(err, gm_id, db_gmail_ids_info, self)
 
             #create the non existing labels and update existing labels
@@ -1015,7 +1015,7 @@ def restore_chats(self, extra_labels = [], restart = False): #pylint:disable=W01
                 self.src.select_folder('ALLMAIL') #go to ALL MAIL to make STORE usable
                 for label in labels_to_apply.keys():
                     self.src.apply_labels_to(labels_to_apply[label], [label]) 
-            except Exception, err:
+            except Exception as err:
                 LOG.error("Problem when applying labels %s to the following ids: %s" %(label, labels_to_apply[label]), err)
                 if isinstance(err, imap_utils.LabelError) and err.ignore() == True:
                     LOG.critical("Ignore labelling: %s" % (err))
@@ -1141,7 +1141,7 @@ def restore_emails(self, pivot_dir = None, extra_labels = [], restart = False):
                     for ex_label in extra_labels: 
                         labels_to_apply[ex_label] = imap_id
                 
-                except Exception, err:
+                except Exception as err:
                     handle_restore_imap_error(err, gm_id, db_gmail_ids_info, self)
 
             #create the non existing labels and update existing labels
@@ -1159,7 +1159,7 @@ def restore_emails(self, pivot_dir = None, extra_labels = [], restart = False):
                 LOG.debug("Changed dir. Operation time = %s ms" % (the_timer.elapsed_ms()))
                 for label in labels_to_apply.keys():
                     self.src.apply_labels_to(labels_to_apply[label], [label]) 
-            except Exception, err:
+            except Exception as err:
                 LOG.error("Problem when applying labels %s to the following ids: %s" %(label, labels_to_apply[label]), err)
                 if isinstance(err, imap_utils.LabelError) and err.ignore() == True:
                     LOG.critical("Ignore labelling: %s" % (err))
diff --git a/src/gmv/gmvault_db.py b/src/gmv/gmvault_db.py
index c06407a2..5d9d2e48 100755
--- a/src/gmv/gmvault_db.py
+++ b/src/gmv/gmvault_db.py
@@ -25,7 +25,10 @@
 import fnmatch
 import shutil
 import codecs
-import StringIO
+try:
+    from StringIO import StringIO ## for Python 2
+except ImportError:
+    from io import StringIO ## for Python 3
 
 import gmv.blowfish as blowfish
 import gmv.log_utils as log_utils
@@ -264,10 +267,10 @@ def parse_header_fields(cls, header_fields):
             try:
                 encod  = gmvault_utils.guess_encoding(tempo, use_encoding_list = False)
                 u_tempo = unicode(tempo, encoding = encod)
-            except gmvault_utils.GuessEncoding, enc_err:
+            except gmvault_utils.GuessEncoding as enc_err:
                   #it is already in unicode so ignore encoding
                   u_tempo = tempo
-            except Exception, e:
+            except Exception as e:
                   LOG.critical(e)
                   LOG.critical("Warning: Guessed encoding = (%s). Ignore those characters" % (encod))
                   #try utf-8
diff --git a/src/gmv/gmvault_utils.py b/src/gmv/gmvault_utils.py
index 9503f98a..e057a798 100755
--- a/src/gmv/gmvault_utils.py
+++ b/src/gmv/gmvault_utils.py
@@ -26,7 +26,11 @@
 import fnmatch
 import functools
 
-import StringIO
+try:
+    from StringIO import StringIO ## for Python 2
+except ImportError:
+    from io import StringIO ## for Python 3
+
 import sys
 import traceback
 import random 
@@ -53,11 +57,11 @@ def __init__(self, func):
     def __call__(self, *args):
         try:
             return self.cache[args]
-        except KeyError:
+        except KeyError as e:
             value = self.func(*args)
             self.cache[args] = value
             return value
-        except TypeError:
+        except TypeError as e:
             # uncachable -- for instance, passing a list as an argument.
             # Better to not cache than to blow up entirely.
             return self.func(*args)
@@ -115,7 +119,7 @@ def get_exception_traceback():
                
     """
    
-    the_file = StringIO.StringIO()
+    the_file = StringIO()
     exception_type, exception_value, exception_traceback = sys.exc_info() #IGNORE:W0702
     traceback.print_exception(exception_type, exception_value, exception_traceback, file = the_file)
     return the_file.getvalue()
@@ -409,9 +413,9 @@ def __rmgeneric(path, __func__):
     """ private function that is part of delete_all_under """
     try:
         __func__(path)
-        #print 'Removed ', path
-    except OSError, (_, strerror): #IGNORE:W0612
-        print """Error removing %(path)s, %(error)s """ % {'path' : path, 'error': strerror }
+        #print('Removed ', path)
+    except OSError as strerror: #IGNORE:W0612
+        print("""Error removing %(path)s, %(error)s """ % {'path' : path, 'error': strerror })
             
 def delete_all_under(path, delete_top_dir = False):
     """ delete all files and directories under path """
@@ -549,7 +553,7 @@ def convert_to_unicode(a_str):
 
         LOG.debug("Convert to %s" % (encoding))
         u_str = unicode(a_str, encoding = encoding) #convert to unicode with given encoding
-    except Exception, e:
+    except Exception as e:
         LOG.debug("Exception: %s" % (e))
         LOG.info("Warning: Guessed encoding = (%s). Ignore those characters" % (encoding if encoding else "Not defined"))
         #try utf-8
@@ -586,7 +590,7 @@ def convert_argv_to_unicode(a_str):
        u_str = a_str.decode(terminal_encoding)
        LOG.debug("unicode_escape val = %s." % (u_str.encode('unicode_escape')))
        LOG.debug("raw unicode     = %s." % (u_str))
-    except Exception, err: 
+    except Exception as err: 
        LOG.error(err)
        get_exception_traceback()
        LOG.info("Convertion of %s from %s to a unicode failed. Will now convert to unicode using utf-8 encoding and ignoring errors (non utf-8 characters will be eaten)." % (a_str, terminal_encoding))
@@ -667,7 +671,7 @@ def _create_default_conf_file(home_conf_file):
         with open(home_conf_file, "w+") as f:
             f.write(gmvault_const.DEFAULT_CONF_FILE)
         return home_conf_file
-    except Exception, err:
+    except Exception as err:
         #catch all error and let run gmvault with defaults if needed
         LOG.critical("Ignore Error when trying to create conf file for defaults in %s:\n%s.\n" % (get_home_dir_path(), err))
         LOG.debug("=== Exception traceback ===")
diff --git a/src/gmv/imap_utils.py b/src/gmv/imap_utils.py
index f30be16c..10f2d620 100755
--- a/src/gmv/imap_utils.py
+++ b/src/gmv/imap_utils.py
@@ -116,7 +116,7 @@ def reconnect(the_self, rec_nb_tries, total_nb_tries, rec_error, rec_sleep_time
                 
                 return 
             
-            except Exception, ignored:
+            except Exception as ignored:
                 # catch all errors and try as long as we have tries left
                 LOG.exception(ignored)
         else:
@@ -130,7 +130,7 @@ def wrapper(*args, **kwargs): #pylint:disable=C0111,R0912
             while True:
                 try:
                     return the_func(*args, **kwargs)
-                except PushEmailError, p_err:
+                except PushEmailError as p_err:
                     
                     LOG.debug("error message = %s. traceback:%s" % (p_err, gmvault_utils.get_exception_traceback()))
                     
@@ -141,7 +141,7 @@ def wrapper(*args, **kwargs): #pylint:disable=C0111,R0912
                     
                     reconnect(args[0], nb_tries, a_nb_tries, p_err, m_sleep_time)
                 
-                except imaplib.IMAP4.abort, err: #abort is recoverable and error is not
+                except imaplib.IMAP4.abort as err: #abort is recoverable and error is not
                     
                     LOG.debug("IMAP (abort) error message = %s. traceback:%s" % (err, gmvault_utils.get_exception_traceback()))
                     
@@ -153,7 +153,7 @@ def wrapper(*args, **kwargs): #pylint:disable=C0111,R0912
                     # problem with this email, put it in quarantine
                     reconnect(args[0], nb_tries, a_nb_tries, err, m_sleep_time)    
                     
-                except socket.error, sock_err:
+                except socket.error as sock_err:
                     LOG.debug("error message = %s. traceback:%s" % (sock_err, gmvault_utils.get_exception_traceback()))
                     
                     if nb_tries[0] < a_nb_tries:
@@ -163,7 +163,7 @@ def wrapper(*args, **kwargs): #pylint:disable=C0111,R0912
                         
                     reconnect(args[0], nb_tries, a_nb_tries, sock_err, m_sleep_time)
                 
-                except ssl.SSLError, ssl_err:
+                except ssl.SSLError as ssl_err:
                     LOG.debug("error message = %s. traceback:%s" % (ssl_err, gmvault_utils.get_exception_traceback()))
                     
                     if nb_tries[0] < a_nb_tries:
@@ -173,7 +173,7 @@ def wrapper(*args, **kwargs): #pylint:disable=C0111,R0912
                         
                     reconnect(args[0], nb_tries, a_nb_tries, sock_err, m_sleep_time)
                 
-                except imaplib.IMAP4.error, err:
+                except imaplib.IMAP4.error as err:
                     
                     #just trace it back for the moment
                     LOG.debug("IMAP (normal) error message = %s. traceback:%s" % (err, gmvault_utils.get_exception_traceback()))
@@ -196,11 +196,11 @@ class GIMAPFetcher(object): #pylint:disable=R0902,R0904
     '''
     IMAP Class reading the information
     '''
-    GMAIL_EXTENSION     = 'X-GM-EXT-1'  # GMAIL capability
-    GMAIL_ALL           = u'[Gmail]/All Mail' #GMAIL All Mail mailbox
+    GMAIL_EXTENSION     = b'X-GM-EXT-1'  # GMAIL capability
+    GMAIL_ALL           = '[Gmail]/All Mail' #GMAIL All Mail mailbox
     
-    GENERIC_GMAIL_ALL   = u'\\AllMail' # unlocalised GMAIL ALL
-    GENERIC_DRAFTS      = u'\\Drafts' # unlocalised DRAFTS
+    GENERIC_GMAIL_ALL   = '\\AllMail' # unlocalised GMAIL ALL
+    GENERIC_DRAFTS      = '\\Drafts' # unlocalised DRAFTS
     GENERIC_GMAIL_CHATS = gmvault_const.GMAIL_UNLOCAL_CHATS   # unlocalised Chats names
     
     FOLDER_NAMES        = ['ALLMAIL', 'CHATS', 'DRAFTS']
@@ -291,6 +291,9 @@ def connect(self, go_to_current_folder = False):
         # connect with password or xoauth
         if self.credential['type'] == 'passwd':
             self.server.login(self.login, self.credential['value'])
+            print(self.server)
+            print(dir(self.server))
+            print(self.server.list_folders())
         elif self.credential['type'] == 'oauth2':
             #connect with oauth2
             if self.once_connected:
@@ -329,7 +332,7 @@ def disconnect(self):
         if self.server:
             try:
                 self.server.logout()
-            except Exception, ignored: #ignored exception but still log it in log file if activated
+            except Exception as ignored: #ignored exception but still log it in log file if activated
                 LOG.exception(ignored)
                 
             self.server = None
@@ -612,7 +615,7 @@ def create_gmail_labels(self, labels, existing_folders):
                             raise Exception("Cannot create label %s: the directory %s cannot be created." % (lab, directory))
                         else:
                             LOG.debug("============== ####### Created Labels (%s)." % (directory))
-                    except imaplib.IMAP4.error, error:
+                    except imaplib.IMAP4.error as error:
                         #log error in log file if it exists
                         LOG.debug(gmvault_utils.get_exception_traceback())
                         if str(error).startswith("create failed: '[ALREADYEXISTS] Duplicate folder"):
@@ -652,7 +655,7 @@ def apply_labels_to(self, imap_ids, labels):
             #+X-GM-LABELS.SILENT to have not returned data
             try:
                 ret_code, data = self.server._imap.uid('STORE', id_list, '+X-GM-LABELS.SILENT', labels_str) #pylint: disable=W0212
-            except imaplib.IMAP4.error, original_err:
+            except imaplib.IMAP4.error as original_err:
                 LOG.info("Error in apply_labels_to. See exception traceback")
                 LOG.debug(gmvault_utils.get_exception_traceback())
                 # try to add labels to each individual ids
@@ -660,7 +663,7 @@ def apply_labels_to(self, imap_ids, labels):
                 for the_id in imap_ids:
                     try:
                        ret_code, data = self.server._imap.uid('STORE', the_id, '+X-GM-LABELS.SILENT', labels_str) #pylint: disable=W0212
-                    except imaplib.IMAP4.error, store_err:
+                    except imaplib.IMAP4.error as store_err:
                        LOG.debug("Error when trying to apply labels %s to emails with imap_id %s. Error:%s" % (labels_str, the_id, store_err))
                        faulty_ids.append(the_id)
                 
@@ -678,7 +681,7 @@ def apply_labels_to(self, imap_ids, labels):
                 for the_id in imap_ids:
                     try:
                        ret_code, data = self.server._imap.uid('STORE', the_id, '+X-GM-LABELS.SILENT', labels_str) #pylint: disable=W0212
-                    except imaplib.IMAP4.error, store_err:
+                    except imaplib.IMAP4.error as store_err:
                        LOG.debug("Error when trying to apply labels %s to emails with imap_id %s. Error:%s" % (labels_str, the_id, store_err))
                        faulty_ids.append(the_id)
 
@@ -700,7 +703,7 @@ def delete_gmail_labels(self, labels, force_delete = False):
                    and self.server.folder_exists(directory) ): #call server exists each time
                     try:
                         self.server.delete_folder(directory)
-                    except imaplib.IMAP4.error, _:
+                    except imaplib.IMAP4.error as _:
                         LOG.debug(gmvault_utils.get_exception_traceback())
     
     
@@ -800,7 +803,7 @@ def push_data(self, a_folder, a_body, a_flags, a_internal_time):
         try:
            #a_body = self._clean_email_body(a_body)
            res = self.server.append(a_folder, a_body, a_flags, a_internal_time)
-        except imaplib.IMAP4.abort, err:
+        except imaplib.IMAP4.abort as err:
            # handle issue when there are invalid characters (This is do to the presence of null characters)
            if str(err).find("APPEND => Invalid character in literal") >= 0:
               LOG.critical("Invalid character detected. Try to clean the email and reconnect.")
@@ -848,7 +851,7 @@ def deprecated_push_email(self, a_body, a_flags, a_internal_time, a_labels):
 
         try:
            res = self.server.append(u'[Google Mail]/All Mail', a_body, a_flags, a_internal_time)
-        except imaplib.IMAP4.abort, err:
+        except imaplib.IMAP4.abort as err:
            # handle issue when there are invalid characters (This is do to the presence of null characters)
            if str(err).find("APPEND => Invalid character in literal") >= 0:
               a_body = self._clean_email_body(a_body)
diff --git a/src/gmv/mod_imap.py b/src/gmv/mod_imap.py
index edbcb160..d181a940 100755
--- a/src/gmv/mod_imap.py
+++ b/src/gmv/mod_imap.py
@@ -24,7 +24,7 @@
 import re
 import socket
 import ssl
-import cStringIO
+from io import StringIO
 import os
 
 import imaplib  #for the exception
@@ -154,12 +154,12 @@ def new_read(self, size):
             Call _intern_read that takes care of the compression
         """
         
-        chunks = cStringIO.StringIO() #use cStringIO.cStringIO to avoir too much fragmentation
+        chunks = StringIO() #use cStringIO.cStringIO to avoir too much fragmentation
         read = 0
         while read < size:
             try:
                 data = self._intern_read(min(size-read, 16384)) #never ask more than 16384 because imaplib can do it
-            except ssl.SSLError, err:
+            except ssl.SSLError as err:
                 print("************* SSLError received %s" % (err)) 
                 raise self.abort('Gmvault ssl socket error: EOF. Connection lost, reconnect.')
             read += len(data)
@@ -173,7 +173,7 @@ def read(self, size):
             Call _intern_read that takes care of the compression
         """
         
-        chunks = cStringIO.StringIO() #use cStringIO.cStringIO to avoir too much fragmentation
+        chunks = StringIO() #use cStringIO.cStringIO to avoir too much fragmentation
         read = 0
         while read < size:
             data = self._intern_read(min(size-read, 16384)) #never ask more than 16384 because imaplib can do it
@@ -202,7 +202,7 @@ def _intern_read(self, size):
         
     def readline(self):
         """Read line from remote."""
-        line = cStringIO.StringIO() #use cStringIO to avoid memory fragmentation
+        line = StringIO() #use cStringIO to avoid memory fragmentation
         while 1:
             #make use of read that takes care of the compression
             #it could be simplified without compression
diff --git a/src/gmv/test_utils.py b/src/gmv/test_utils.py
index 274579e8..1655f5fc 100755
--- a/src/gmv/test_utils.py
+++ b/src/gmv/test_utils.py
@@ -435,7 +435,7 @@ def get_oauth_cred(email, cred_path):
                 if len(oauth_result) == 2:
                     token  = oauth_result[0]
                     secret = oauth_result[1]
-        except Exception, _: #pylint: disable-msg=W0703              
+        except Exception as _: #pylint: disable-msg=W0703              
             print("Cannot read oauth credentials from %s. Force oauth credentials renewal." % user_oauth_file_path)
             print("=== Exception traceback ===")
             print(gmvault_utils.get_exception_traceback())
diff --git a/src/gmv_cmd_tests.py b/src/gmv_cmd_tests.py
index 358d566c..2e91a2f3 100755
--- a/src/gmv_cmd_tests.py
+++ b/src/gmv_cmd_tests.py
@@ -250,7 +250,7 @@ def zztest_cli_bad_server(self):
     
             gmvaulter.run(args)
         
-        except SystemExit, _:
+        except SystemExit as _:
             print("In Error success")
             
     def ztest_cli_bad_passwd(self):
@@ -270,7 +270,7 @@ def ztest_cli_bad_passwd(self):
     
             gmvaulter.run(args)
         
-        except SystemExit, err:
+        except SystemExit as err:
             print("In Error success")
             
     def ztest_cli_bad_login(self):
@@ -290,7 +290,7 @@ def ztest_cli_bad_login(self):
     
             gmvaulter.run(args)
         
-        except SystemExit, err:
+        except SystemExit as err:
             print("In Error success")
             
     
@@ -307,10 +307,10 @@ def zztest_cli_host_error(self):
     
         try:
             _ = gmvaulter.parse_args()
-        except SystemExit, err:
+        except SystemExit as err:
             self.assertEquals(type(err), type(SystemExit()))
             self.assertEquals(err.code, 2)
-        except Exception, err:
+        except Exception as err:
             self.fail('unexpected exception: %s' % err)
         else:
             self.fail('SystemExit exception expected')
@@ -339,9 +339,9 @@ def zztest_cli_(self):
             self.assertEquals(args['port'], 993)
             self.assertEquals(args['db-dir'],'./gmvault-db')
             
-        except SystemExit, err:
+        except SystemExit as err:
             self.fail("SystemExit Exception: %s"  % err)
-        except Exception, err:
+        except Exception as err:
             self.fail('unexpected exception: %s' % err)
     
     def ztest_full_sync_gmv(self):
diff --git a/src/gmvault_tests.py b/src/gmvault_tests.py
index dc205179..ecf3ed8a 100755
--- a/src/gmvault_tests.py
+++ b/src/gmvault_tests.py
@@ -82,7 +82,7 @@ def ztest_gmvault_connect_error(self):
         
         try:
             gimap.connect()
-        except ssl.SSLError, err:
+        except ssl.SSLError as err:
             
             msg = str(err)
             
@@ -285,7 +285,7 @@ def ztest_retrieve_gmail_ids(self):
         
         res = gimap.fetch(ids, [gimap.GMAIL_ID])
         
-        self.assertEquals(res, {27362: {'X-GM-MSGID': 1147537963432096749L, 'SEQ': 14535}, 27363: {'X-GM-MSGID': 1147537994018957026L, 'SEQ': 14536}})
+        self.assertEquals(res, {27362: {'X-GM-MSGID': 1147537963432096749, 'SEQ': 14535}, 27363: {'X-GM-MSGID': 1147537994018957026, 'SEQ': 14536}})
         
     def ztest_retrieve_all_params(self):
         """
@@ -304,7 +304,7 @@ def ztest_retrieve_all_params(self):
         
         res = gimap.fetch(ids[0], [gimap.GMAIL_ID, gimap.EMAIL_BODY, gimap.GMAIL_THREAD_ID, gimap.GMAIL_LABELS])
         
-        self.assertEquals(res[ids[0]][gimap.GMAIL_ID], 1147537963432096749L)
+        self.assertEquals(res[ids[0]][gimap.GMAIL_ID], 1147537963432096749)
         
         self.assertEquals(res[ids[0]][gimap.EMAIL_BODY], \
                           'Message-ID: <6999505.1094377483218.JavaMail.wwwadm@chewbacca.ecmwf.int>\r\nDate: Sun, 5 Sep 2004 09:44:43 +0000 (GMT)\r\nFrom: Guillaume.Aubert@ecmwf.int\r\nReply-To: Guillaume.Aubert@ecmwf.int\r\nTo: aubert_guillaume@yahoo.fr\r\nSubject: Fwd: [Flickr] Guillaume Aubert wants you to see their photos\r\nMime-Version: 1.0\r\nContent-Type: text/plain; charset=us-ascii\r\nContent-Transfer-Encoding: 7bit\r\nX-Mailer: jwma\r\nStatus: RO\r\nX-Status: \r\nX-Keywords:                 \r\nX-UID: 1\r\n\r\n\r\n') #pylint:disable-msg=C0301
@@ -681,7 +681,7 @@ def ztest_fix_bug(self):
         credential = { 'type' : 'passwd', 'value': self.passwd}
         syncer = gmvault.GMVaulter(db_dir, 'imap.gmail.com', 993, self.login, credential, 'verySecRetKeY')
         
-        syncer._create_update_sync([142221L], compress = True)
+        syncer._create_update_sync([142221], compress = True)
         
     def test_check_flags(self):
         """
diff --git a/src/sandbox/chardet_test.py b/src/sandbox/chardet_test.py
index 1b4bd964..55fab1a7 100644
--- a/src/sandbox/chardet_test.py
+++ b/src/sandbox/chardet_test.py
@@ -7,17 +7,17 @@
 first_arg = sys.argv[1]
 #first_arg="réception"
 #first_arg="て感じでしょうか研"
-print first_arg
+print(first_arg)
 print("chardet = %s\n" % chardet.detect(first_arg))
 res_char = chardet.detect(first_arg)
-print type(first_arg)
+print(type(first_arg))
  
 
  
 first_arg_unicode = first_arg.decode(res_char['encoding'])
-print first_arg_unicode
-print type(first_arg_unicode)
+print(first_arg_unicode)
+print(type(first_arg_unicode))
  
 utf8_arg = first_arg_unicode.encode("utf-8")
-print type(utf8_arg)
-print utf8_arg
\ No newline at end of file
+print(type(utf8_arg))
+print(utf8_arg)
diff --git a/src/sandbox/pycrypto_test.py b/src/sandbox/pycrypto_test.py
index bbf04eaf..bccedf1b 100644
--- a/src/sandbox/pycrypto_test.py
+++ b/src/sandbox/pycrypto_test.py
@@ -38,8 +38,8 @@ def _unpad(s):
     key="This is my key"
     enc = AESEncryptor(key)
     for secret in secrets:
-        print "Secret:", secret
+        print("Secret:", secret)
         encrypted = enc.encrypt(secret) 
-        print "Encrypted secret:", encrypted
-        print "Clear Secret:" , enc.decrypt(encrypted)
-        print '-' *50
+        print("Encrypted secret:", encrypted)
+        print("Clear Secret:" , enc.decrypt(encrypted))
+        print('-' *50)
diff --git a/src/sandbox/unicode_test.py b/src/sandbox/unicode_test.py
index 22e64bc4..2cba93e8 100644
--- a/src/sandbox/unicode_test.py
+++ b/src/sandbox/unicode_test.py
@@ -12,12 +12,12 @@ def convert_to_utf8(a_str):
     """
     """
     if type(a_str) != type(u'a'):
-		#import chardet
-		#char_enc = chardet.detect(a_str)
-		#print("detected encoding = %s" % (char_enc))
-		#print("system machine encoding = %s" % (sys.getdefaultencoding()))
-		#u_str = unicode(a_str, char_enc['encoding'], errors='ignore')
-		u_str = unicode(a_str, 'cp437', errors='ignore')
+        #import chardet
+        #char_enc = chardet.detect(a_str)
+        #print("detected encoding = %s" % (char_enc))
+        #print("system machine encoding = %s" % (sys.getdefaultencoding()))
+        #u_str = unicode(a_str, char_enc['encoding'], errors='ignore')
+        u_str = unicode(a_str, 'cp437', errors='ignore')
     else:
         print("Already unicode do not convert")
         u_str = a_str