diff --git a/src/yunohost/app.py b/src/yunohost/app.py
index d32fb59a2..05580fbe1 100644
--- a/src/yunohost/app.py
+++ b/src/yunohost/app.py
@@ -30,10 +30,10 @@ import shutil
 import yaml
 import time
 import re
-import urlparse
+import urllib.parse
 import subprocess
 import glob
-import urllib
+import urllib.request, urllib.parse, urllib.error
 from collections import OrderedDict
 
 from moulinette import msignals, m18n, msettings
@@ -736,7 +736,7 @@ def app_install(operation_logger, app, label=None, args=None, no_remove_on_failu
 
     # Retrieve arguments list for install script
     args_dict = {} if not args else \
-        dict(urlparse.parse_qsl(args, keep_blank_values=True))
+        dict(urllib.parse.parse_qsl(args, keep_blank_values=True))
     args_odict = _parse_args_from_manifest(manifest, 'install', args=args_dict)
 
     # Validate domain / path availability for webapps
@@ -759,7 +759,7 @@ def app_install(operation_logger, app, label=None, args=None, no_remove_on_failu
     # Also redact the % escaped version of the password that might appear in
     # the 'args' section of metadata (relevant for password with non-alphanumeric char)
     data_to_redact = [value[0] for value in args_odict.values() if value[1] == "password"]
-    data_to_redact += [urllib.quote(data) for data in data_to_redact if urllib.quote(data) != data]
+    data_to_redact += [urllib.parse.quote(data) for data in data_to_redact if urllib.parse.quote(data) != data]
     operation_logger.data_to_redact.extend(data_to_redact)
 
     operation_logger.related_to = [s for s in operation_logger.related_to if s[0] != "app"]
@@ -1406,7 +1406,7 @@ def app_ssowatconf():
 
     write_to_json('/etc/ssowat/conf.json', conf_dict, sort_keys=True, indent=4)
 
-    from utils.legacy import translate_legacy_rules_in_ssowant_conf_json_persistent
+    from .utils.legacy import translate_legacy_rules_in_ssowant_conf_json_persistent
     translate_legacy_rules_in_ssowant_conf_json_persistent()
 
     logger.debug(m18n.n('ssowat_conf_generated'))
@@ -1456,7 +1456,7 @@ def app_action_run(operation_logger, app, action, args=None):
     action_declaration = actions[action]
 
     # Retrieve arguments list for install script
-    args_dict = dict(urlparse.parse_qsl(args, keep_blank_values=True)) if args else {}
+    args_dict = dict(urllib.parse.parse_qsl(args, keep_blank_values=True)) if args else {}
     args_odict = _parse_args_for_action(actions[action], args=args_dict)
     args_list = [value[0] for value in args_odict.values()]
 
@@ -1598,7 +1598,7 @@ def app_config_apply(operation_logger, app, args):
         "YNH_APP_INSTANCE_NAME": app,
         "YNH_APP_INSTANCE_NUMBER": str(app_instance_nb),
     }
-    args = dict(urlparse.parse_qsl(args, keep_blank_values=True)) if args else {}
+    args = dict(urllib.parse.parse_qsl(args, keep_blank_values=True)) if args else {}
 
     for tab in config_panel.get("panel", []):
         tab_id = tab["id"]  # this makes things easier to debug on crash
@@ -1817,8 +1817,7 @@ def _get_app_config_panel(app_id):
             "panel": [],
         }
 
-        panels = filter(lambda key_value: key_value[0] not in ("name", "version") and isinstance(key_value[1], OrderedDict),
-                        toml_config_panel.items())
+        panels = [key_value for key_value in toml_config_panel.items() if key_value[0] not in ("name", "version") and isinstance(key_value[1], OrderedDict)]
 
         for key, value in panels:
             panel = {
@@ -1827,8 +1826,7 @@ def _get_app_config_panel(app_id):
                 "sections": [],
             }
 
-            sections = filter(lambda k_v1: k_v1[0] not in ("name",) and isinstance(k_v1[1], OrderedDict),
-                              value.items())
+            sections = [k_v1 for k_v1 in value.items() if k_v1[0] not in ("name",) and isinstance(k_v1[1], OrderedDict)]
 
             for section_key, section_value in sections:
                 section = {
@@ -1837,8 +1835,7 @@ def _get_app_config_panel(app_id):
                     "options": [],
                 }
 
-                options = filter(lambda k_v: k_v[0] not in ("name",) and isinstance(k_v[1], OrderedDict),
-                                 section_value.items())
+                options = [k_v for k_v in section_value.items() if k_v[0] not in ("name",) and isinstance(k_v[1], OrderedDict)]
 
                 for option_key, option_value in options:
                     option = dict(option_value)
@@ -2315,7 +2312,7 @@ def _encode_string(value):
     """
     Return the string encoded in utf-8 if needed
     """
-    if isinstance(value, unicode):
+    if isinstance(value, str):
         return value.encode('utf8')
     return value
 
@@ -2926,7 +2923,7 @@ def _load_apps_catalog():
         try:
             apps_catalog_content = read_json(cache_file) if os.path.exists(cache_file) else None
         except Exception as e:
-            raise ("Unable to read cache for apps_catalog %s : %s" % (apps_catalog_id, str(e)))
+            raise "Unable to read cache for apps_catalog %s : %s"
 
         # Check that the version of the data matches version ....
         # ... otherwise it means we updated yunohost in the meantime
@@ -2976,7 +2973,7 @@ def is_true(arg):
     """
     if isinstance(arg, bool):
         return arg
-    elif isinstance(arg, basestring):
+    elif isinstance(arg, str):
         return arg.lower() in ['yes', 'true', 'on']
     else:
         logger.debug('arg should be a boolean or a string, got %r', arg)
diff --git a/src/yunohost/backup.py b/src/yunohost/backup.py
index c0f11eae8..7c75837b0 100644
--- a/src/yunohost/backup.py
+++ b/src/yunohost/backup.py
@@ -882,7 +882,7 @@ class RestoreManager():
         End a restore operations by cleaning the working directory and
         regenerate ssowat conf (if some apps were restored)
         """
-        from permission import permission_sync_to_user
+        from .permission import permission_sync_to_user
 
         permission_sync_to_user()
 
diff --git a/src/yunohost/certificate.py b/src/yunohost/certificate.py
index c9451c2be..fc81ae0a6 100644
--- a/src/yunohost/certificate.py
+++ b/src/yunohost/certificate.py
@@ -385,7 +385,7 @@ def certificate_renew(domain_list, force=False, no_checks=False, email=False, st
             _fetch_and_enable_new_certificate(domain, staging, no_checks=no_checks)
         except Exception as e:
             import traceback
-            from StringIO import StringIO
+            from io import StringIO
             stack = StringIO()
             traceback.print_exc(file=stack)
             msg = "Certificate renewing for %s failed !" % (domain)
diff --git a/src/yunohost/dyndns.py b/src/yunohost/dyndns.py
index fe2a1bc9b..e43c180ad 100644
--- a/src/yunohost/dyndns.py
+++ b/src/yunohost/dyndns.py
@@ -105,7 +105,7 @@ def _dyndns_available(provider, domain):
         raise YunohostError('dyndns_could_not_check_available',
                             domain=domain, provider=provider)
 
-    return r == u"Domain %s is available" % domain
+    return r == "Domain %s is available" % domain
 
 
 @is_unit_operation()
diff --git a/src/yunohost/log.py b/src/yunohost/log.py
index cf108b989..a21ddd606 100644
--- a/src/yunohost/log.py
+++ b/src/yunohost/log.py
@@ -65,8 +65,7 @@ def log_list(limit=None, with_details=False, with_suboperations=False):
 
     operations = {}
 
-    logs = filter(lambda x: x.endswith(METADATA_FILE_EXT),
-                  os.listdir(OPERATIONS_PATH))
+    logs = [x for x in os.listdir(OPERATIONS_PATH) if x.endswith(METADATA_FILE_EXT)]
     logs = list(reversed(sorted(logs)))
 
     if limit is not None:
@@ -337,7 +336,7 @@ def is_unit_operation(entities=['app', 'domain', 'group', 'service', 'user'],
                     entity_type = entity
 
                 if entity in kwargs and kwargs[entity] is not None:
-                    if isinstance(kwargs[entity], basestring):
+                    if isinstance(kwargs[entity], str):
                         related_to.append((entity_type, kwargs[entity]))
                     else:
                         for x in kwargs[entity]:
@@ -596,7 +595,7 @@ class OperationLogger(object):
         """
         if self.ended_at is not None or self.started_at is None:
             return
-        if error is not None and not isinstance(error, basestring):
+        if error is not None and not isinstance(error, str):
             error = str(error)
         self.ended_at = datetime.utcnow()
         self._error = error
diff --git a/src/yunohost/settings.py b/src/yunohost/settings.py
index 3c79d7945..060aca6e4 100644
--- a/src/yunohost/settings.py
+++ b/src/yunohost/settings.py
@@ -29,7 +29,7 @@ def is_boolean(value):
     """
     if isinstance(value, bool):
         return True, value
-    elif isinstance(value, basestring):
+    elif isinstance(value, str):
         if str(value).lower() in ['true', 'on', 'yes', 'false', 'off', 'no']:
             return True, str(value).lower() in ['true', 'on', 'yes']
         else:
@@ -141,7 +141,7 @@ def settings_set(key, value):
                 raise YunohostError('global_settings_bad_type_for_setting', setting=key,
                                     received_type=type(value).__name__, expected_type=key_type)
     elif key_type == "string":
-        if not isinstance(value, basestring):
+        if not isinstance(value, str):
             raise YunohostError('global_settings_bad_type_for_setting', setting=key,
                                 received_type=type(value).__name__, expected_type=key_type)
     elif key_type == "enum":
diff --git a/src/yunohost/tests/test_apps.py b/src/yunohost/tests/test_apps.py
index 0f4c3749a..baa3d5181 100644
--- a/src/yunohost/tests/test_apps.py
+++ b/src/yunohost/tests/test_apps.py
@@ -4,7 +4,7 @@ import pytest
 import shutil
 import requests
 
-from conftest import message, raiseYunohostError, get_test_apps_dir
+from .conftest import message, raiseYunohostError, get_test_apps_dir
 
 from moulinette.utils.filesystem import mkdir
 
diff --git a/src/yunohost/tests/test_apps_arguments_parsing.py b/src/yunohost/tests/test_apps_arguments_parsing.py
index 88c235252..dfe17d229 100644
--- a/src/yunohost/tests/test_apps_arguments_parsing.py
+++ b/src/yunohost/tests/test_apps_arguments_parsing.py
@@ -2,7 +2,7 @@ import sys
 import pytest
 
 from mock import patch
-from StringIO import StringIO
+from io import StringIO
 from collections import OrderedDict
 
 from moulinette import msignals
diff --git a/src/yunohost/tests/test_appurl.py b/src/yunohost/tests/test_appurl.py
index 11ee7b4f5..3a2313b0e 100644
--- a/src/yunohost/tests/test_appurl.py
+++ b/src/yunohost/tests/test_appurl.py
@@ -1,7 +1,7 @@
 import pytest
 import os
 
-from conftest import get_test_apps_dir
+from .conftest import get_test_apps_dir
 
 from yunohost.utils.error import YunohostError
 from yunohost.app import app_install, app_remove, _normalize_domain_path
diff --git a/src/yunohost/tests/test_backuprestore.py b/src/yunohost/tests/test_backuprestore.py
index 9c9448879..b88fbd5b3 100644
--- a/src/yunohost/tests/test_backuprestore.py
+++ b/src/yunohost/tests/test_backuprestore.py
@@ -3,7 +3,7 @@ import os
 import shutil
 import subprocess
 
-from conftest import message, raiseYunohostError, get_test_apps_dir
+from .conftest import message, raiseYunohostError, get_test_apps_dir
 
 from yunohost.app import app_install, app_remove, app_ssowatconf
 from yunohost.app import _is_installed
diff --git a/src/yunohost/tests/test_changeurl.py b/src/yunohost/tests/test_changeurl.py
index ecd926a2e..ef076e67b 100644
--- a/src/yunohost/tests/test_changeurl.py
+++ b/src/yunohost/tests/test_changeurl.py
@@ -3,7 +3,7 @@ import time
 import requests
 import os
 
-from conftest import get_test_apps_dir
+from .conftest import get_test_apps_dir
 
 from yunohost.app import app_install, app_change_url, app_remove, app_map
 from yunohost.domain import _get_maindomain
diff --git a/src/yunohost/tests/test_permission.py b/src/yunohost/tests/test_permission.py
index 1d3961585..a1f411b80 100644
--- a/src/yunohost/tests/test_permission.py
+++ b/src/yunohost/tests/test_permission.py
@@ -6,7 +6,7 @@ import os
 import json
 import shutil
 
-from conftest import message, raiseYunohostError, get_test_apps_dir
+from .conftest import message, raiseYunohostError, get_test_apps_dir
 
 from yunohost.app import app_install, app_upgrade, app_remove, app_change_url, app_map, _installed_apps, APPS_SETTING_PATH, _set_app_settings, _get_app_settings
 from yunohost.user import user_list, user_create, user_delete, \
diff --git a/src/yunohost/tests/test_regenconf.py b/src/yunohost/tests/test_regenconf.py
index 4e1ae679b..c9a3e68f5 100644
--- a/src/yunohost/tests/test_regenconf.py
+++ b/src/yunohost/tests/test_regenconf.py
@@ -1,6 +1,6 @@
 import os
 
-from conftest import message
+from .conftest import message
 from yunohost.domain import domain_add, domain_remove, domain_list
 from yunohost.regenconf import regen_conf, manually_modified_files, _get_conf_hashes, _force_clear_hashes
 
diff --git a/src/yunohost/tests/test_service.py b/src/yunohost/tests/test_service.py
index d0a3d4fc2..0c65a864a 100644
--- a/src/yunohost/tests/test_service.py
+++ b/src/yunohost/tests/test_service.py
@@ -1,6 +1,6 @@
 import os
 
-from conftest import raiseYunohostError
+from .conftest import raiseYunohostError
 
 from yunohost.service import _get_services, _save_services, service_status, service_add, service_remove, service_log
 
diff --git a/src/yunohost/tests/test_user-group.py b/src/yunohost/tests/test_user-group.py
index c0f51e35a..31131e939 100644
--- a/src/yunohost/tests/test_user-group.py
+++ b/src/yunohost/tests/test_user-group.py
@@ -1,6 +1,6 @@
 import pytest
 
-from conftest import message, raiseYunohostError
+from .conftest import message, raiseYunohostError
 
 from yunohost.user import user_list, user_info, user_create, user_delete, user_update, \
     user_group_list, user_group_create, user_group_delete, user_group_update
diff --git a/src/yunohost/tools.py b/src/yunohost/tools.py
index 96bd01ed6..f01f6adb8 100644
--- a/src/yunohost/tools.py
+++ b/src/yunohost/tools.py
@@ -303,7 +303,7 @@ def tools_postinstall(operation_logger, domain, password, ignore_dyndns=False,
         '/home/yunohost.app'
     ]
 
-    for folder in filter(lambda x: not os.path.exists(x), folders_to_create):
+    for folder in [x for x in folders_to_create if not os.path.exists(x)]:
         os.makedirs(folder)
 
     # Change folders permissions
@@ -953,7 +953,7 @@ def _get_migrations_list():
     # (in particular, pending migrations / not already ran are not listed
     states = tools_migrations_state()["migrations"]
 
-    for migration_file in filter(lambda x: re.match(r"^\d+_[a-zA-Z0-9_]+\.py$", x), os.listdir(migrations_path)):
+    for migration_file in [x for x in os.listdir(migrations_path) if re.match(r"^\d+_[a-zA-Z0-9_]+\.py$", x)]:
         m = _load_migration(migration_file)
         m.state = states.get(m.id, "pending")
         migrations.append(m)
@@ -972,7 +972,7 @@ def _get_migration_by_name(migration_name):
         raise AssertionError("Unable to find migration with name %s" % migration_name)
 
     migrations_path = data_migrations.__path__[0]
-    migrations_found = filter(lambda x: re.match(r"^\d+_%s\.py$" % migration_name, x), os.listdir(migrations_path))
+    migrations_found = [x for x in os.listdir(migrations_path) if re.match(r"^\d+_%s\.py$" % migration_name, x)]
 
     assert len(migrations_found) == 1, "Unable to find migration with name %s" % migration_name