diff --git a/tools/dependency_inventory.py b/tools/dependency_inventory.py
index 36479a024..ff82fbb27 100644
--- a/tools/dependency_inventory.py
+++ b/tools/dependency_inventory.py
@@ -165,7 +165,6 @@ def get_js_deps():
         if module[2] != "":
             licence = module[2]
 
-        url = "Unknown"
         if module[3] != "":
             url = module[3]
 
diff --git a/web/pgadmin/browser/server_groups/servers/__init__.py b/web/pgadmin/browser/server_groups/servers/__init__.py
index 870da543b..78200b69e 100644
--- a/web/pgadmin/browser/server_groups/servers/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/__init__.py
@@ -1016,9 +1016,11 @@ class ServerNode(PGChildNodeView):
         else:
             return unauthorized(gettext("Unauthorized request."))
 
-        data = request.form if request.form else json.loads(
-            request.data, encoding='utf-8'
-        ) if request.data else {}
+        data = {}
+        if request.form:
+            data = request.form
+        elif request.data:
+            data = json.loads(request.data, encoding='utf-8')
 
         password = None
         passfile = None
diff --git a/web/pgadmin/browser/server_groups/servers/databases/__init__.py b/web/pgadmin/browser/server_groups/servers/databases/__init__.py
index 6c6472583..52fb050d8 100644
--- a/web/pgadmin/browser/server_groups/servers/databases/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/databases/__init__.py
@@ -862,8 +862,6 @@ class DatabaseView(PGChildNodeView):
                 )
             else:
 
-                status = self.manager.release(did=did)
-
                 SQL = render_template(
                     "/".join([self.template_path, self._DELETE_SQL]),
                     datname=res, conn=self.conn
diff --git a/web/pgadmin/browser/server_groups/servers/databases/schemas/foreign_tables/__init__.py b/web/pgadmin/browser/server_groups/servers/databases/schemas/foreign_tables/__init__.py
index 3d8697a9d..60bfc9af8 100644
--- a/web/pgadmin/browser/server_groups/servers/databases/schemas/foreign_tables/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/databases/schemas/foreign_tables/__init__.py
@@ -305,9 +305,12 @@ class ForeignTableView(PGChildNodeView, DataTypeReader,
                                     data[key] = []
 
                     elif key == 'typnotnull':
-                        data[key] = True if (req[key] == 'true' or req[key]
-                                             is True) else False if \
-                            (req[key] == 'false' or req[key]) is False else ''
+                        if req[key] == 'true' or req[key] is True:
+                            data[key] = True
+                        elif req[key] == 'false' or req[key] is False:
+                            data[key] = False
+                        else:
+                            data[key] = ''
                     else:
                         data[key] = req[key]
 
diff --git a/web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/__init__.py b/web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/__init__.py
index eeed70eb5..0fbdbca1a 100644
--- a/web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/__init__.py
@@ -450,7 +450,7 @@ class PartitionsView(BaseTableView, DataTypeReader, VacuumSettings,
                 )
                 res[row['name']] = data
 
-            return res
+        return res
 
     @BaseTableView.check_precondition
     def sql(self, gid, sid, did, scid, tid, ptid):
diff --git a/web/pgadmin/browser/server_groups/servers/databases/schemas/types/__init__.py b/web/pgadmin/browser/server_groups/servers/databases/schemas/types/__init__.py
index fea69fb0d..5fb2b8cfe 100644
--- a/web/pgadmin/browser/server_groups/servers/databases/schemas/types/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/databases/schemas/types/__init__.py
@@ -473,15 +473,15 @@ class TypeView(PGChildNodeView, DataTypeReader, SchemaDiffObjectCompare):
 
                 # If we have length & precision both
                 if is_tlength and is_precision:
-                    matchObj = re.search(r'(\d+),(\d+)', row['fulltype'])
-                    if matchObj:
-                        t_len = matchObj.group(1)
-                        t_prec = matchObj.group(2)
+                    match_obj = re.search(r'(\d+),(\d+)', row['fulltype'])
+                    if match_obj:
+                        t_len = match_obj.group(1)
+                        t_prec = match_obj.group(2)
                 elif is_tlength:
                     # If we have length only
-                    matchObj = re.search(r'(\d+)', row['fulltype'])
-                    if matchObj:
-                        t_len = matchObj.group(1)
+                    match_obj = re.search(r'(\d+)', row['fulltype'])
+                    if match_obj:
+                        t_len = match_obj.group(1)
                         t_prec = None
 
                 type_name = DataTypeReader.parse_type_name(row['typname'])
diff --git a/web/pgadmin/misc/bgprocess/processes.py b/web/pgadmin/misc/bgprocess/processes.py
index d73e6d783..efaaf2075 100644
--- a/web/pgadmin/misc/bgprocess/processes.py
+++ b/web/pgadmin/misc/bgprocess/processes.py
@@ -202,25 +202,6 @@ class BatchProcess(object):
                     return file_quote(exe_file)
             return None
 
-        def convert_environment_variables(env):
-            """
-            This function is use to convert environment variable to string
-            because environment variable must be string in popen
-            :param env: Dict of environment variable
-            :return: Encoded environment variable as string
-            """
-            encoding = sys.getdefaultencoding()
-            if encoding is None or encoding == 'ascii':
-                encoding = 'utf-8'
-            temp_env = dict()
-            for key, value in env.items():
-                if not isinstance(key, str):
-                    key = key.encode(encoding)
-                if not isinstance(value, str):
-                    value = value.encode(encoding)
-                temp_env[key] = value
-            return temp_env
-
         if self.stime is not None:
             if self.etime is None:
                 raise Exception(_('The process has already been started.'))
@@ -409,7 +390,7 @@ class BatchProcess(object):
         out_completed = err_completed = False
         process_output = (out != -1 and err != -1)
         enc = sys.getdefaultencoding()
-        if enc is None or enc == 'ascii':
+        if enc == 'ascii':
             enc = 'utf-8'
 
         def read_log(logfile, log, pos, ctime, ecode=None):
diff --git a/web/pgadmin/misc/file_manager/__init__.py b/web/pgadmin/misc/file_manager/__init__.py
index 78a24c24a..b6dab51bd 100644
--- a/web/pgadmin/misc/file_manager/__init__.py
+++ b/web/pgadmin/misc/file_manager/__init__.py
@@ -671,29 +671,28 @@ class Filemanager(object):
     @staticmethod
     def check_access_permission(in_dir, path):
 
-        if not config.SERVER_MODE:
-            return True
+        if config.SERVER_MODE:
+            if in_dir is None:
+                in_dir = ""
+            orig_path = Filemanager.get_abs_path(in_dir, path)
 
-        if in_dir is None:
-            in_dir = ""
-        orig_path = Filemanager.get_abs_path(in_dir, path)
+            # This translates path with relative path notations
+            # like ./ and ../ to absolute path.
+            orig_path = os.path.abspath(orig_path)
 
-        # This translates path with relative path notations like ./ and ../ to
-        # absolute path.
-        orig_path = os.path.abspath(orig_path)
+            if in_dir:
+                if _platform == 'win32':
+                    if in_dir[-1] == '\\' or in_dir[-1] == '/':
+                        in_dir = in_dir[:-1]
+                else:
+                    if in_dir[-1] == '/':
+                        in_dir = in_dir[:-1]
 
-        if in_dir:
-            if _platform == 'win32':
-                if in_dir[-1] == '\\' or in_dir[-1] == '/':
-                    in_dir = in_dir[:-1]
-            else:
-                if in_dir[-1] == '/':
-                    in_dir = in_dir[:-1]
-
-        # Do not allow user to access outside his storage dir in server mode.
-        if not orig_path.startswith(in_dir):
-            raise Exception(
-                gettext(u"Access denied ({0})").format(path))
+            # Do not allow user to access outside his storage dir
+            # in server mode.
+            if not orig_path.startswith(in_dir):
+                raise Exception(
+                    gettext(u"Access denied ({0})").format(path))
         return True
 
     @staticmethod
diff --git a/web/pgadmin/tools/debugger/__init__.py b/web/pgadmin/tools/debugger/__init__.py
index 9b5bf5ddd..3209e4f0a 100644
--- a/web/pgadmin/tools/debugger/__init__.py
+++ b/web/pgadmin/tools/debugger/__init__.py
@@ -492,7 +492,6 @@ def init_function(node_type, sid, did, scid, fid, trid=None):
             for pr_arg_mode in pro_arg_modes:
                 if pr_arg_mode == 'o' or pr_arg_mode == 't':
                     data['require_input'] = False
-                    continue
                 else:
                     data['require_input'] = True
                     break
@@ -2124,7 +2123,8 @@ def close_debugger_session(_trans_id, close_all=False):
                                 dbg_obj['exe_conn_id'],
                                 dbg_obj['database_id'])
                         manager.release(conn_id=dbg_obj['exe_conn_id'])
-        except Exception:
-            raise
-        finally:
+
             de_inst.clear()
+        except Exception:
+            de_inst.clear()
+            raise
diff --git a/web/pgadmin/tools/schema_diff/directory_compare.py b/web/pgadmin/tools/schema_diff/directory_compare.py
index 4841322b1..0fe730623 100644
--- a/web/pgadmin/tools/schema_diff/directory_compare.py
+++ b/web/pgadmin/tools/schema_diff/directory_compare.py
@@ -319,7 +319,7 @@ def are_dictionaries_identical(source_dict, target_dict, ignore_whitespaces,
     return True
 
 
-def directory_diff(source_dict, target_dict, ignore_keys=[], difference={}):
+def directory_diff(source_dict, target_dict, ignore_keys=[], difference=None):
     """
     This function is used to recursively compare two dictionaries and
     return the difference.
@@ -330,6 +330,7 @@ def directory_diff(source_dict, target_dict, ignore_keys=[], difference={}):
     :param difference:
     """
 
+    difference = {} if difference is None else difference
     src_keys = set(source_dict.keys())
     tar_keys = set(target_dict.keys())
 
diff --git a/web/pgadmin/tools/sqleditor/__init__.py b/web/pgadmin/tools/sqleditor/__init__.py
index 0ec573b0e..58bb6cde8 100644
--- a/web/pgadmin/tools/sqleditor/__init__.py
+++ b/web/pgadmin/tools/sqleditor/__init__.py
@@ -259,10 +259,7 @@ def start_view_data(trans_id):
         update_session_grid_transaction(trans_id, session_obj)
 
         # Execute sql asynchronously
-        try:
-            status, result = conn.execute_async(sql)
-        except (ConnectionLost, SSHTunnelConnectionLost) as e:
-            raise
+        status, result = conn.execute_async(sql)
     else:
         status = False
         result = error_msg
diff --git a/web/pgadmin/tools/sqleditor/utils/start_running_query.py b/web/pgadmin/tools/sqleditor/utils/start_running_query.py
index b4d213992..cddd64ecd 100644
--- a/web/pgadmin/tools/sqleditor/utils/start_running_query.py
+++ b/web/pgadmin/tools/sqleditor/utils/start_running_query.py
@@ -137,10 +137,7 @@ class StartRunningQuery:
 
         # Execute sql asynchronously with params is None
         # and formatted_error is True.
-        try:
-            status, result = conn.execute_async(sql)
-        except (ConnectionLost, SSHTunnelConnectionLost, CryptKeyMissing):
-            raise
+        status, result = conn.execute_async(sql)
 
         # If the transaction aborted for some reason and
         # Auto RollBack is True then issue a rollback to cleanup.
diff --git a/web/pgadmin/utils/ajax.py b/web/pgadmin/utils/ajax.py
index acde2793b..7c37d20ed 100644
--- a/web/pgadmin/utils/ajax.py
+++ b/web/pgadmin/utils/ajax.py
@@ -31,7 +31,7 @@ class DataTypeJSONEncoder(json.JSONEncoder):
 
 
 class ColParamsJSONDecoder(json.JSONDecoder):
-    def decode(self, obj):
+    def decode(self, obj, **kwargs):
         retval = obj
         try:
             retval = json.JSONDecoder.decode(self, obj)
diff --git a/web/pgadmin/utils/csv.py b/web/pgadmin/utils/csv.py
index ee586991c..fd67df230 100644
--- a/web/pgadmin/utils/csv.py
+++ b/web/pgadmin/utils/csv.py
@@ -721,7 +721,7 @@ class DictWriter(object):
             raise ValueError("extrasaction (%s) must be 'raise' or 'ignore'"
                              % self.extrasaction)
         dialect = kwds.get('dialect', "excel")
-        self.Writer = Writer(f, dialect, *args, **kwds)
+        self.writer = Writer(f, dialect, *args, **kwds)
 
     def writeheader(self):
         header = dict(zip(self.fieldnames, self.fieldnames))
@@ -736,7 +736,7 @@ class DictWriter(object):
         return (rowdict.get(key, self.restval) for key in self.fieldnames)
 
     def writerow(self, rowdict):
-        return self.Writer.writerow(self._dict_to_list(rowdict))
+        return self.writer.writerow(self._dict_to_list(rowdict))
 
     def writerows(self, rowdicts):
-        return self.Writer.writerows(map(self._dict_to_list, rowdicts))
+        return self.writer.writerows(map(self._dict_to_list, rowdicts))
diff --git a/web/pgadmin/utils/driver/psycopg2/connection.py b/web/pgadmin/utils/driver/psycopg2/connection.py
index 9c78b502e..33af4f57c 100644
--- a/web/pgadmin/utils/driver/psycopg2/connection.py
+++ b/web/pgadmin/utils/driver/psycopg2/connection.py
@@ -198,12 +198,7 @@ class Connection(BaseConnection):
         )
 
     def __str__(self):
-        return "PG Connection: {0} ({1}) -> {2} (ajax:{3})".format(
-            self.conn_id, self.db,
-            'Connected' if self.conn and not self.conn.closed else
-            "Disconnected",
-            self.async_
-        )
+        return self.__repr__()
 
     def connect(self, **kwargs):
         if self.conn:
@@ -714,27 +709,6 @@ WHERE
             return False, \
                 gettext('The query executed did not return any data.')
 
-        def convert_keys_to_unicode(results, conn_encoding):
-            """
-            [ This is only for Python2.x]
-            We need to convert all keys to unicode as psycopg2
-            sends them as string
-
-            Args:
-                res: Query result set from psycopg2
-                conn_encoding: Connection encoding
-
-            Returns:
-                Result set (With all the keys converted to unicode)
-            """
-            new_results = []
-            for row in results:
-                new_results.append(
-                    dict([(k.decode(conn_encoding), v)
-                          for k, v in row.items()])
-                )
-            return new_results
-
         def handle_null_values(results, replace_nulls_with):
             """
             This function is used to replace null values with the given string
@@ -1279,9 +1253,14 @@ WHERE
             )
 
         except psycopg2.Error as e:
-            msg = e.pgerror if e.pgerror else e.message \
-                if e.message else e.diag.message_detail \
-                if e.diag.message_detail else str(e)
+            if e.pgerror:
+                msg = e.pgerror
+            elif e.message:
+                msg = e.message
+            elif e.diag.message_detail:
+                msg = e.diag.message_detail
+            else:
+                msg = str(e)
 
             current_app.logger.error(
                 gettext(
diff --git a/web/pgadmin/utils/driver/psycopg2/server_manager.py b/web/pgadmin/utils/driver/psycopg2/server_manager.py
index 923046e70..ce11a31f1 100644
--- a/web/pgadmin/utils/driver/psycopg2/server_manager.py
+++ b/web/pgadmin/utils/driver/psycopg2/server_manager.py
@@ -372,8 +372,11 @@ WHERE db.oid = {0}""".format(did))
             else:
                 return False
 
-        my_id = (u'CONN:{0}'.format(conn_id)) if conn_id is not None else \
-            (u'DB:{0}'.format(database)) if database is not None else None
+        my_id = None
+        if conn_id is not None:
+            my_id = u'CONN:{0}'.format(conn_id)
+        elif database is not None:
+            my_id = u'DB:{0}'.format(database)
 
         if my_id is not None:
             if my_id in self.connections:
diff --git a/web/pgadmin/utils/session.py b/web/pgadmin/utils/session.py
index a8b94142f..177a996b8 100644
--- a/web/pgadmin/utils/session.py
+++ b/web/pgadmin/utils/session.py
@@ -103,11 +103,11 @@ class SessionManager(object):
 
 
 class CachingSessionManager(SessionManager):
-    def __init__(self, parent, num_to_store, skip_paths=[]):
+    def __init__(self, parent, num_to_store, skip_paths=None):
         self.parent = parent
         self.num_to_store = num_to_store
         self._cache = OrderedDict()
-        self.skip_paths = skip_paths
+        self.skip_paths = [] if skip_paths is None else skip_paths
 
     def _normalize(self):
         if len(self._cache) > self.num_to_store:
@@ -187,13 +187,13 @@ class CachingSessionManager(SessionManager):
 
 class FileBackedSessionManager(SessionManager):
 
-    def __init__(self, path, secret, disk_write_delay, skip_paths=[]):
+    def __init__(self, path, secret, disk_write_delay, skip_paths=None):
         self.path = path
         self.secret = secret
         self.disk_write_delay = disk_write_delay
         if not os.path.exists(self.path):
             os.makedirs(self.path)
-        self.skip_paths = skip_paths
+        self.skip_paths = [] if skip_paths is None else skip_paths
 
     def exists(self, sid):
         fname = os.path.join(self.path, sid)
diff --git a/web/regression/python_test_utils/test_utils.py b/web/regression/python_test_utils/test_utils.py
index 2f36b5e81..b93d8ad19 100644
--- a/web/regression/python_test_utils/test_utils.py
+++ b/web/regression/python_test_utils/test_utils.py
@@ -1129,9 +1129,9 @@ def check_binary_path_or_skip_test(cls, utility_name):
             cls.server['default_binary_paths'][cls.server['type']],
             utility_name
         )
-        ret_val = does_utility_exist(binary_path)
-        if ret_val is not None:
-            cls.skipTest(ret_val)
+        retVal = does_utility_exist(binary_path)
+        if retVal is not None:
+            cls.skipTest(retVal)
 
 
 def get_watcher_dialogue_status(self):
diff --git a/web/regression/runtests.py b/web/regression/runtests.py
index 73d3eb7ba..86c5a0a8e 100644
--- a/web/regression/runtests.py
+++ b/web/regression/runtests.py
@@ -819,6 +819,7 @@ if __name__ == '__main__':
                             app_starter_local.stop_app()
                         if handle_cleanup:
                             handle_cleanup()
+                        raise
             else:
                 print(
                     "\n============= Either Selenium Grid is NOT up OR"
@@ -840,6 +841,7 @@ if __name__ == '__main__':
         except SystemExit:
             if handle_cleanup:
                 handle_cleanup()
+            raise
         print_test_results()
 
     # Stop code coverage