diff --git a/web/pgAdmin4.py b/web/pgAdmin4.py
index ce7f1f39d..fdab437ba 100644
--- a/web/pgAdmin4.py
+++ b/web/pgAdmin4.py
@@ -32,20 +32,20 @@ if config.SERVER_MODE is True:
     local_config = os.path.join(os.path.dirname(os.path.realpath(__file__)),
                                 'config_local.py')
     if not os.path.isfile(local_config):
-        print "The configuration file %s does not exist.\n" % local_config
-        print "Before running this application, ensure that config_local.py has been created"
-        print "and sets values for SECRET_KEY, SECURITY_PASSWORD_SALT and CSRF_SESSION_KEY"
-        print "at bare minimum. See config.py for more information and a complete list of"
-        print "settings. Exiting..."
+        print("The configuration file %s does not exist.\n" % local_config)
+        print("Before running this application, ensure that config_local.py has been created")
+        print("and sets values for SECRET_KEY, SECURITY_PASSWORD_SALT and CSRF_SESSION_KEY")
+        print("at bare minimum. See config.py for more information and a complete list of")
+        print("settings. Exiting...")
         sys.exit(1)
 
 # Check if the database exists. If it does not, tell the user and exit.
 if not os.path.isfile(config.SQLITE_PATH):
-    print "The configuration database %s does not exist.\n" \
-            % config.SQLITE_PATH
-    print "Please run 'python %s' to create it.\nExiting..." % os.path.join(
+    print("The configuration database %s does not exist.\n" \
+            % config.SQLITE_PATH)
+    print("Please run 'python %s' to create it.\nExiting..." % os.path.join(
             os.path.dirname(os.path.realpath(__file__)), 'setup.py'
-            )
+            ))
     sys.exit(1)
 
 ##########################################################################
diff --git a/web/pgadmin/__init__.py b/web/pgadmin/__init__.py
index d0e4df1ca..0b5273504 100644
--- a/web/pgadmin/__init__.py
+++ b/web/pgadmin/__init__.py
@@ -16,7 +16,7 @@ from flask.ext.security import Security, SQLAlchemyUserDatastore
 from flask_security.utils import login_user
 from flask_mail import Mail
 from htmlmin.minify import html_minify
-from settings.settings_model import db, Role, User, Version
+from pgadmin.settings.settings_model import db, Role, User, Version
 from importlib import import_module
 from werkzeug.local import LocalProxy
 from pgadmin.utils import PgAdminModule, driver
@@ -40,9 +40,9 @@ class PgAdmin(Flask):
                 continue
             self.logger.info('Examining potential module: %s' % module_name)
             module = import_module(module_name)
-            for key, value in module.__dict__.items():
-                if isinstance(value, PgAdminModule):
-                    yield value
+            for key in list(module.__dict__.keys()):
+                if isinstance(module.__dict__[key], PgAdminModule):
+                    yield module.__dict__[key]
 
     @property
     def submodules(self):
diff --git a/web/pgadmin/browser/__init__.py b/web/pgadmin/browser/__init__.py
index 5d9e02b3c..876e93224 100644
--- a/web/pgadmin/browser/__init__.py
+++ b/web/pgadmin/browser/__init__.py
@@ -16,10 +16,10 @@ from flask.ext.security import login_required
 from flask.ext.login import current_user
 from flask.ext.babel import gettext
 from flaskext.gravatar import Gravatar
+import six
 
 MODULE_NAME = 'browser'
 
-
 class BrowserModule(PgAdminModule):
 
     def get_own_stylesheets(self):
@@ -136,20 +136,18 @@ class BrowserModule(PgAdminModule):
 
         for module in self.submodules:
             scripts.extend(module.get_own_javascripts())
-
         return scripts
 
 
 blueprint = BrowserModule(MODULE_NAME, __name__)
 
-
+@six.add_metaclass(ABCMeta)
 class BrowserPluginModule(PgAdminModule):
     """
     Base class for browser submodules.
     """
 
     browser_url_prefix = blueprint.url_prefix + '/'
-    __metaclass__ = ABCMeta
 
     def __init__(self, import_name, **kwargs):
         kwargs.setdefault("url_prefix", self.node_path)
@@ -178,7 +176,6 @@ class BrowserPluginModule(PgAdminModule):
 
         for module in self.submodules:
             scripts.extend(module.get_own_javascripts())
-
         return scripts
 
     def generate_browser_node(
@@ -213,7 +210,6 @@ class BrowserPluginModule(PgAdminModule):
 
         for submodule in self.submodules:
             snippets.extend(submodule.csssnippets)
-
         return snippets
 
     @abstractmethod
diff --git a/web/pgadmin/browser/server_groups/__init__.py b/web/pgadmin/browser/server_groups/__init__.py
index 3afcd7e1f..5ecfd3d7d 100644
--- a/web/pgadmin/browser/server_groups/__init__.py
+++ b/web/pgadmin/browser/server_groups/__init__.py
@@ -21,7 +21,7 @@ from pgadmin.browser import BrowserPluginModule
 from pgadmin.utils.menu import MenuItem
 from pgadmin.settings.settings_model import db, ServerGroup
 from pgadmin.browser.utils import NodeView
-
+import six
 
 class ServerGroupModule(BrowserPluginModule):
 
@@ -55,13 +55,12 @@ class ServerGroupMenuItem(MenuItem):
         kwargs.setdefault("type", ServerGroupModule.NODE_TYPE)
         super(ServerGroupMenuItem, self).__init__(**kwargs)
 
-
+@six.add_metaclass(ABCMeta)
 class ServerGroupPluginModule(BrowserPluginModule):
     """
     Base class for server group plugins.
     """
 
-    __metaclass__ = ABCMeta
 
     @abstractmethod
     def get_nodes(self, *arg, **kwargs):
@@ -119,7 +118,7 @@ class ServerGroupView(NodeView):
                 user_id=current_user.id,
                 id=gid).first()
 
-        data = request.form if request.form else json.loads(request.data)
+        data = request.form if request.form else json.loads(request.data.decode())
 
         if servergroup is None:
             return make_json_response(
@@ -165,8 +164,7 @@ class ServerGroupView(NodeView):
                     )
 
     def create(self):
-        data = request.form if request.form else json.loads(request.data)
-
+        data = request.form if request.form else json.loads(request.data.decode())
         if data[u'name'] != '':
             try:
                 sg = ServerGroup(
@@ -177,7 +175,7 @@ class ServerGroupView(NodeView):
 
                 data[u'id'] = sg.id
                 data[u'name'] = sg.name
-
+                
                 return jsonify(
                         node=self.blueprint.generate_browser_node(
                             "%d" % (sg.id),
diff --git a/web/pgadmin/browser/server_groups/servers/__init__.py b/web/pgadmin/browser/server_groups/servers/__init__.py
index ba4eca84a..db56dbdf3 100644
--- a/web/pgadmin/browser/server_groups/servers/__init__.py
+++ b/web/pgadmin/browser/server_groups/servers/__init__.py
@@ -22,7 +22,7 @@ import pgadmin.browser.server_groups as sg
 from pgadmin.utils.crypto import encrypt, decrypt
 from pgadmin.browser import BrowserPluginModule
 from config import PG_DEFAULT_DRIVER
-
+import six
 
 class ServerModule(sg.ServerGroupPluginModule):
     NODE_TYPE = "server"
@@ -90,13 +90,12 @@ class ServerMenuItem(MenuItem):
 
 blueprint = ServerModule(__name__)
 
-
+@six.add_metaclass(ABCMeta)
 class ServerTypeModule(BrowserPluginModule):
     """
     Base class for different server types.
     """
 
-    __metaclass__ = ABCMeta
 
     @abstractproperty
     def type(self):
@@ -381,7 +380,7 @@ class ServerNode(NodeView):
             u'role'
         ]
 
-        data = request.form if request.form else json.loads(request.data)
+        data = request.form if request.form else json.loads(request.data.decode())
 
         for arg in required_args:
             if arg not in data:
@@ -577,7 +576,10 @@ class ServerNode(NodeView):
             # TODO::
             # Ask the password again (if existing password couldn't be
             # descrypted)
-            return internal_server_error(errormsg=e.message)
+            if e.message:
+                return internal_server_error(errormsg=e.message)
+            else:
+                return internal_server_error(errormsg=str(e)) 
 
         if not status:
             current_app.logger.error(
diff --git a/web/pgadmin/browser/utils.py b/web/pgadmin/browser/utils.py
index 87b125d16..89e2ff03a 100644
--- a/web/pgadmin/browser/utils.py
+++ b/web/pgadmin/browser/utils.py
@@ -14,16 +14,16 @@ from collections import OrderedDict
 import flask
 from flask.views import View, MethodViewType, with_metaclass
 from flask.ext.babel import gettext
+import six
 
 from config import PG_DEFAULT_DRIVER
 from pgadmin.browser import PgAdminModule
 from pgadmin.utils.ajax import make_json_response
 
-
+@six.add_metaclass(ABCMeta)
 class NodeAttr(object):
     """
     """
-    __metaclass__ = ABCMeta
 
     @abstractmethod
     def validate(self, mode, value):
diff --git a/web/pgadmin/settings/__init__.py b/web/pgadmin/settings/__init__.py
index 7d6ac731d..99359b318 100644
--- a/web/pgadmin/settings/__init__.py
+++ b/web/pgadmin/settings/__init__.py
@@ -13,7 +13,7 @@ from flask import current_app
 from flask.ext.login import current_user
 from flask.ext.sqlalchemy import SQLAlchemy
 
-from settings_model import db, Setting
+from .settings_model import db, Setting
 import traceback
 from flask import Blueprint, Response, abort, request, render_template
 from flask.ext.security import login_required
diff --git a/web/pgadmin/utils/crypto.py b/web/pgadmin/utils/crypto.py
index dff06864a..efe5905ae 100644
--- a/web/pgadmin/utils/crypto.py
+++ b/web/pgadmin/utils/crypto.py
@@ -12,7 +12,7 @@ from Crypto.Cipher import AES
 from Crypto import Random
 import base64
 
-padding_string = '}'
+padding_string = b'}'
 
 
 def encrypt(plaintext, key):
diff --git a/web/pgadmin/utils/driver/abstract.py b/web/pgadmin/utils/driver/abstract.py
index 8292cc8cb..2fba2698f 100644
--- a/web/pgadmin/utils/driver/abstract.py
+++ b/web/pgadmin/utils/driver/abstract.py
@@ -9,8 +9,9 @@
 from abc import ABCMeta, abstractmethod, abstractproperty
 from flask import session
 from .registry import DriverRegistry
+import six
 
-
+@six.add_metaclass(DriverRegistry)
 class BaseDriver(object):
     """
     class BaseDriver(object):
@@ -40,7 +41,6 @@ class BaseDriver(object):
       session, which has not been pinged from more than the idle timeout
       configuration.
     """
-    __metaclass__ = DriverRegistry
 
     @abstractproperty
     def Version(cls):
@@ -58,7 +58,7 @@ class BaseDriver(object):
     def gc(self):
         pass
 
-
+@six.add_metaclass(ABCMeta)
 class BaseConnection(object):
     """
     class BaseConnection(object)
@@ -113,7 +113,6 @@ class BaseConnection(object):
             connection object for better memory management, and connection pool
             management.
     """
-    __metaclass__ = ABCMeta
 
     @abstractmethod
     def connect(self, **kwargs):
diff --git a/web/pgadmin/utils/driver/psycopg2/__init__.py b/web/pgadmin/utils/driver/psycopg2/__init__.py
index 33f8ec339..8125bfef8 100644
--- a/web/pgadmin/utils/driver/psycopg2/__init__.py
+++ b/web/pgadmin/utils/driver/psycopg2/__init__.py
@@ -111,9 +111,12 @@ class Connection(BaseConnection):
                     )
 
         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.diag.message_detail:
+                msg = e.diag.message_detail
+            else:
+                msg = str(e)
 
             return False, msg
 
diff --git a/web/setup.py b/web/setup.py
index df3276f8b..9f430ae14 100644
--- a/web/setup.py
+++ b/web/setup.py
@@ -47,7 +47,7 @@ Enter the email address and password to use for the initial pgAdmin user \
 account:\n""")
         email = ''
         while email == '':
-            email = raw_input("Email address: ")
+            email = input("Email address: ")
 
         def pprompt():
             return getpass.getpass(), getpass.getpass('Retype password:')