diff --git a/vcsserver/config/settings_maker.py b/vcsserver/config/settings_maker.py
--- a/vcsserver/config/settings_maker.py
+++ b/vcsserver/config/settings_maker.py
@@ -72,7 +72,7 @@ class SettingsMaker(object):
             os.makedirs(input_val, mode=mode, exist_ok=True)
 
         if not os.path.isdir(input_val):
-            raise Exception('Dir at {} does not exist'.format(input_val))
+            raise Exception(f'Dir at {input_val} does not exist')
         return input_val
 
     @classmethod
diff --git a/vcsserver/git_lfs/app.py b/vcsserver/git_lfs/app.py
--- a/vcsserver/git_lfs/app.py
+++ b/vcsserver/git_lfs/app.py
@@ -212,7 +212,7 @@ def lfs_objects_verify(request):
 
     store_size = store.size_oid()
     if store_size != size:
-        msg = 'requested file size mismatch store size:%s requested:%s' % (
+        msg = 'requested file size mismatch store size:{} requested:{}'.format(
             store_size, size)
         return write_response_error(
             HTTPUnprocessableEntity, msg)
diff --git a/vcsserver/git_lfs/lib.py b/vcsserver/git_lfs/lib.py
--- a/vcsserver/git_lfs/lib.py
+++ b/vcsserver/git_lfs/lib.py
@@ -51,7 +51,7 @@ class OidHandler(object):
 
         if not store.has_oid():
             # error reply back to client that something is wrong with dl
-            err_msg = 'object: {} does not exist in store'.format(store.oid)
+            err_msg = f'object: {store.oid} does not exist in store'
             has_errors = OrderedDict(
                 error=OrderedDict(
                     code=404,
diff --git a/vcsserver/hook_utils/__init__.py b/vcsserver/hook_utils/__init__.py
--- a/vcsserver/hook_utils/__init__.py
+++ b/vcsserver/hook_utils/__init__.py
@@ -75,7 +75,7 @@ def install_git_hooks(repo_path, bare, e
                     template = template.replace(b'_PATH_', safe_bytes(path))
                     f.write(template)
                 os.chmod(_hook_file, 0o755)
-            except IOError:
+            except OSError:
                 log.exception('error writing hook file %s', _hook_file)
         else:
             log.debug('skipping writing hook file')
@@ -129,7 +129,7 @@ def install_svn_hooks(repo_path, executa
 
                     f.write(template)
                 os.chmod(_hook_file, 0o755)
-            except IOError:
+            except OSError:
                 log.exception('error writing hook file %s', _hook_file)
         else:
             log.debug('skipping writing hook file')
diff --git a/vcsserver/lib/_vendor/jsonlogger/__init__.py b/vcsserver/lib/_vendor/jsonlogger/__init__.py
--- a/vcsserver/lib/_vendor/jsonlogger/__init__.py
+++ b/vcsserver/lib/_vendor/jsonlogger/__init__.py
@@ -84,7 +84,7 @@ class JsonEncoder(json.JSONEncoder):
             return str(obj)
 
         try:
-            return super(JsonEncoder, self).default(obj)
+            return super().default(obj)
 
         except TypeError:
             try:
@@ -200,7 +200,7 @@ class JsonFormatter(ExceptionAwareFormat
 
     def serialize_log_record(self, log_record):
         """Returns the final representation of the log record."""
-        return "%s%s" % (self.prefix, self.jsonify_log_record(log_record))
+        return "{}{}".format(self.prefix, self.jsonify_log_record(log_record))
 
     def format(self, record):
         """Formats a log record and serializes to json"""
diff --git a/vcsserver/lib/_vendor/redis_lock/__init__.py b/vcsserver/lib/_vendor/redis_lock/__init__.py
--- a/vcsserver/lib/_vendor/redis_lock/__init__.py
+++ b/vcsserver/lib/_vendor/redis_lock/__init__.py
@@ -219,7 +219,7 @@ class Lock(object):
 
         if self._held:
             owner_id = self.get_owner_id()
-            raise AlreadyAcquired("Already acquired from this Lock instance. Lock id: {}".format(owner_id))
+            raise AlreadyAcquired(f"Already acquired from this Lock instance. Lock id: {owner_id}")
 
         if not blocking and timeout is not None:
             raise TimeoutNotUsable("Timeout cannot be used if blocking=False")
diff --git a/vcsserver/lib/_vendor/statsd/__init__.py b/vcsserver/lib/_vendor/statsd/__init__.py
--- a/vcsserver/lib/_vendor/statsd/__init__.py
+++ b/vcsserver/lib/_vendor/statsd/__init__.py
@@ -1,5 +1,3 @@
-
-
 import logging
 
 from .stream import TCPStatsClient, UnixSocketStatsClient  # noqa
diff --git a/vcsserver/lib/_vendor/statsd/base.py b/vcsserver/lib/_vendor/statsd/base.py
--- a/vcsserver/lib/_vendor/statsd/base.py
+++ b/vcsserver/lib/_vendor/statsd/base.py
@@ -1,5 +1,3 @@
-
-
 import re
 import random
 from collections import deque
diff --git a/vcsserver/lib/_vendor/statsd/stream.py b/vcsserver/lib/_vendor/statsd/stream.py
--- a/vcsserver/lib/_vendor/statsd/stream.py
+++ b/vcsserver/lib/_vendor/statsd/stream.py
@@ -1,5 +1,3 @@
-
-
 import socket
 
 from .base import StatsClientBase, PipelineBase
diff --git a/vcsserver/lib/_vendor/statsd/timer.py b/vcsserver/lib/_vendor/statsd/timer.py
--- a/vcsserver/lib/_vendor/statsd/timer.py
+++ b/vcsserver/lib/_vendor/statsd/timer.py
@@ -1,5 +1,3 @@
-
-
 import functools
 from time import perf_counter as time_now
 
diff --git a/vcsserver/lib/_vendor/statsd/udp.py b/vcsserver/lib/_vendor/statsd/udp.py
--- a/vcsserver/lib/_vendor/statsd/udp.py
+++ b/vcsserver/lib/_vendor/statsd/udp.py
@@ -1,5 +1,3 @@
-
-
 import socket
 
 from .base import StatsClientBase, PipelineBase
@@ -8,7 +6,7 @@ from .base import StatsClientBase, Pipel
 class Pipeline(PipelineBase):
 
     def __init__(self, client):
-        super(Pipeline, self).__init__(client)
+        super().__init__(client)
         self._maxudpsize = client._maxudpsize
 
     def _send(self):
diff --git a/vcsserver/lib/logging_formatter.py b/vcsserver/lib/logging_formatter.py
--- a/vcsserver/lib/logging_formatter.py
+++ b/vcsserver/lib/logging_formatter.py
@@ -43,7 +43,7 @@ class ColorFormatter(logging.Formatter):
         """
         Change record's levelname to use with COLORS enum
         """
-        def_record = super(ColorFormatter, self).format(record)
+        def_record = super().format(record)
 
         levelname = record.levelname
         start = COLOR_SEQ % (COLORS[levelname])
diff --git a/vcsserver/lib/memory_lru_dict.py b/vcsserver/lib/memory_lru_dict.py
--- a/vcsserver/lib/memory_lru_dict.py
+++ b/vcsserver/lib/memory_lru_dict.py
@@ -51,11 +51,11 @@ class LRUDictDebug(LRUDict):
     Wrapper to provide some debug options
     """
     def _report_keys(self):
-        elems_cnt = '{}/{}'.format(len(list(self.keys())), self.size)
+        elems_cnt = f'{len(list(self.keys()))}/{self.size}'
         # trick for pformat print it more nicely
         fmt = '\n'
         for cnt, elem in enumerate(self.keys()):
-            fmt += '{} - {}\n'.format(cnt+1, safe_str(elem))
+            fmt += f'{cnt+1} - {safe_str(elem)}\n'
         log.debug('current LRU keys (%s):%s', elems_cnt, fmt)
 
     def __getitem__(self, key):
diff --git a/vcsserver/lib/rc_cache/utils.py b/vcsserver/lib/rc_cache/utils.py
--- a/vcsserver/lib/rc_cache/utils.py
+++ b/vcsserver/lib/rc_cache/utils.py
@@ -173,7 +173,7 @@ def get_or_create_region(region_name, re
     region_obj = region_meta.dogpile_cache_regions.get(region_name)
     if not region_obj:
         reg_keys = list(region_meta.dogpile_cache_regions.keys())
-        raise EnvironmentError(f'Region `{region_name}` not in configured: {reg_keys}.')
+        raise OSError(f'Region `{region_name}` not in configured: {reg_keys}.')
 
     region_uid_name = f'{region_name}:{region_namespace}'
 
diff --git a/vcsserver/remote/git.py b/vcsserver/remote/git.py
--- a/vcsserver/remote/git.py
+++ b/vcsserver/remote/git.py
@@ -483,7 +483,7 @@ class GitRemote(RemoteBase):
 
         q = {"service": 'git-upload-pack'}
         qs = '?%s' % urllib.parse.urlencode(q)
-        cu = "{}{}".format(test_uri, qs)
+        cu = f"{test_uri}{qs}"
         req = urllib.request.Request(cu, None, {})
 
         try:
@@ -494,7 +494,7 @@ class GitRemote(RemoteBase):
         except Exception as e:
             log.warning("URL cannot be opened: %s", obfuscated_uri, exc_info=True)
             # means it cannot be cloned
-            raise exceptions.URLError(e)("[{}] org_exc: {}".format(obfuscated_uri, e))
+            raise exceptions.URLError(e)(f"[{obfuscated_uri}] org_exc: {e}")
 
         # now detect if it's proper git repo
         gitdata: bytes = resp.read()
diff --git a/vcsserver/remote/hg.py b/vcsserver/remote/hg.py
--- a/vcsserver/remote/hg.py
+++ b/vcsserver/remote/hg.py
@@ -464,7 +464,7 @@ class HgRemote(RemoteBase):
         q = {"cmd": 'between'}
         q.update({'pairs': "{}-{}".format('0' * 40, '0' * 40)})
         qs = '?%s' % urllib.parse.urlencode(q)
-        cu = "{}{}".format(test_uri, qs)
+        cu = f"{test_uri}{qs}"
         req = urllib.request.Request(cu, None, {})
 
         try:
@@ -475,7 +475,7 @@ class HgRemote(RemoteBase):
         except Exception as e:
             log.warning("URL cannot be opened: %s", obfuscated_uri, exc_info=True)
             # means it cannot be cloned
-            raise exceptions.URLError(e)("[{}] org_exc: {}".format(obfuscated_uri, e))
+            raise exceptions.URLError(e)(f"[{obfuscated_uri}] org_exc: {e}")
 
         # now check if it's a proper hg repo, but don't do it for svn
         try:
diff --git a/vcsserver/subprocessio.py b/vcsserver/subprocessio.py
--- a/vcsserver/subprocessio.py
+++ b/vcsserver/subprocessio.py
@@ -42,11 +42,11 @@ class StreamFeeder(threading.Thread):
     """
 
     def __init__(self, source):
-        super(StreamFeeder, self).__init__()
+        super().__init__()
         self.daemon = True
         filelike = False
-        self.bytes = bytes()
-        if type(source) in (type(''), bytes, bytearray):  # string-like
+        self.bytes = b''
+        if type(source) in (str, bytes, bytearray):  # string-like
             self.bytes = bytes(source)
         else:  # can be either file pointer or file-like
             if isinstance(source, int):  # file pointer it is
@@ -85,7 +85,7 @@ class StreamFeeder(threading.Thread):
 class InputStreamChunker(threading.Thread):
     def __init__(self, source, target, buffer_size, chunk_size):
 
-        super(InputStreamChunker, self).__init__()
+        super().__init__()
 
         self.daemon = True  # die die die.
 
@@ -440,7 +440,7 @@ class SubprocessIOChunker(object):
             elif err and fail_on_stderr:
                 text_err = err.decode()
                 raise OSError(
-                    "Subprocess exited due to an error:\n{}".format(text_err))
+                    f"Subprocess exited due to an error:\n{text_err}")
 
             if ret_code_fail and fail_on_return_code:
                 text_err = err.decode()
@@ -449,7 +449,7 @@ class SubprocessIOChunker(object):
                     # in many cases git reports the errors on stdout too
                     text_err = out.decode()
                 raise OSError(
-                    "Subprocess exited with non 0 ret code:{}: stderr:{}".format(return_code, text_err))
+                    f"Subprocess exited with non 0 ret code:{return_code}: stderr:{text_err}")
 
         self.stdout = bg_out
         self.stderr = bg_err
@@ -482,7 +482,7 @@ class SubprocessIOChunker(object):
                 self.stop_streams()
                 err = self.get_stderr()
                 raise OSError(
-                    "Subprocess exited (exit_code:{}) due to an error during iteration:\n{}".format(return_code, err))
+                    f"Subprocess exited (exit_code:{return_code}) due to an error during iteration:\n{err}")
 
         if stop_iteration:
             raise stop_iteration
diff --git a/vcsserver/tweens/request_wrapper.py b/vcsserver/tweens/request_wrapper.py
--- a/vcsserver/tweens/request_wrapper.py
+++ b/vcsserver/tweens/request_wrapper.py
@@ -103,15 +103,15 @@ class RequestWrapperTween(object):
                 statsd.timing(
                     "vcsserver_req_timing.histogram", elapsed_time_ms,
                     tags=[
-                        "view_name:{}".format(match_route),
-                        "code:{}".format(resp_code)
+                        f"view_name:{match_route}",
+                        f"code:{resp_code}"
                     ],
                     use_decimals=False
                 )
                 statsd.incr(
                     "vcsserver_req_total", tags=[
-                        "view_name:{}".format(match_route),
-                        "code:{}".format(resp_code)
+                        f"view_name:{match_route}",
+                        f"code:{resp_code}"
                     ])
 
         return response