diff --git a/rhodecode/apps/file_store/utils.py b/rhodecode/apps/file_store/utils.py
--- a/rhodecode/apps/file_store/utils.py
+++ b/rhodecode/apps/file_store/utils.py
@@ -20,7 +20,7 @@
 
 
 import uuid
-import StringIO
+from io import StringIO
 import pathlib2
 
 
diff --git a/rhodecode/lib/_vendor/authomatic/six.py b/rhodecode/lib/_vendor/authomatic/six.py
--- a/rhodecode/lib/_vendor/authomatic/six.py
+++ b/rhodecode/lib/_vendor/authomatic/six.py
@@ -627,7 +627,7 @@ else:
     def indexbytes(buf, i):
         return ord(buf[i])
     iterbytes = functools.partial(itertools.imap, ord)
-    import StringIO
+    from io import StringIO
     StringIO = BytesIO = StringIO.StringIO
     _assertCountEqual = "assertItemsEqual"
     _assertRaisesRegex = "assertRaisesRegexp"
diff --git a/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py b/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
--- a/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
@@ -4,7 +4,7 @@
    At the moment, this isn't so much based off of ANSI as much as
    things that just happen to work with multiple databases.
 """
-import StringIO
+from io import StringIO
 
 import sqlalchemy as sa
 from sqlalchemy.schema import SchemaVisitor
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/script/py.py b/rhodecode/lib/dbmigrate/migrate/versioning/script/py.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/script/py.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/script/py.py
@@ -5,7 +5,7 @@ import shutil
 import warnings
 import logging
 import inspect
-from StringIO import StringIO
+from io import StringIO
 
 from rhodecode.lib.dbmigrate import migrate
 from rhodecode.lib.dbmigrate.migrate.versioning import genmodel, schemadiff
diff --git a/rhodecode/lib/feedgenerator/feedgenerator.py b/rhodecode/lib/feedgenerator/feedgenerator.py
--- a/rhodecode/lib/feedgenerator/feedgenerator.py
+++ b/rhodecode/lib/feedgenerator/feedgenerator.py
@@ -33,7 +33,7 @@ http://web.archive.org/web/2011071803522
 
 
 import datetime
-from StringIO import StringIO
+from io import StringIO
 
 import pytz
 from six.moves.urllib import parse as urlparse
diff --git a/rhodecode/lib/helpers.py b/rhodecode/lib/helpers.py
--- a/rhodecode/lib/helpers.py
+++ b/rhodecode/lib/helpers.py
@@ -30,7 +30,7 @@ import collections
 import os
 import random
 import hashlib
-import StringIO
+from io import StringIO
 import textwrap
 import urllib.request, urllib.parse, urllib.error
 import math
diff --git a/rhodecode/lib/middleware/simplevcs.py b/rhodecode/lib/middleware/simplevcs.py
--- a/rhodecode/lib/middleware/simplevcs.py
+++ b/rhodecode/lib/middleware/simplevcs.py
@@ -28,7 +28,7 @@ import re
 import logging
 import importlib
 from functools import wraps
-from StringIO import StringIO
+from io import StringIO
 from lxml import etree
 
 import time
diff --git a/rhodecode/lib/vcs/backends/git/commit.py b/rhodecode/lib/vcs/backends/git/commit.py
--- a/rhodecode/lib/vcs/backends/git/commit.py
+++ b/rhodecode/lib/vcs/backends/git/commit.py
@@ -25,7 +25,7 @@ GIT commit module
 import re
 import stat
 from itertools import chain
-from StringIO import StringIO
+from io import StringIO
 
 from zope.cachedescriptors.property import Lazy as LazyProperty
 
diff --git a/rhodecode/tests/lib/middleware/test_simplesvn.py b/rhodecode/tests/lib/middleware/test_simplesvn.py
--- a/rhodecode/tests/lib/middleware/test_simplesvn.py
+++ b/rhodecode/tests/lib/middleware/test_simplesvn.py
@@ -18,7 +18,7 @@
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
-from StringIO import StringIO
+from io import StringIO
 
 import pytest
 from mock import patch, Mock
diff --git a/rhodecode/tests/lib/test_hooks_daemon.py b/rhodecode/tests/lib/test_hooks_daemon.py
--- a/rhodecode/tests/lib/test_hooks_daemon.py
+++ b/rhodecode/tests/lib/test_hooks_daemon.py
@@ -20,7 +20,7 @@
 
 import json
 import logging
-from StringIO import StringIO
+from io import StringIO
 
 import mock
 import pytest
diff --git a/rhodecode/tests/vcs/test_archives.py b/rhodecode/tests/vcs/test_archives.py
--- a/rhodecode/tests/vcs/test_archives.py
+++ b/rhodecode/tests/vcs/test_archives.py
@@ -24,7 +24,7 @@ import shutil
 import tarfile
 import tempfile
 import zipfile
-import StringIO
+from io import StringIO
 
 import mock
 import pytest