diff --git a/changelog.d/3668.misc b/changelog.d/3668.misc
new file mode 100644
index 0000000000..f9265addf1
--- /dev/null
+++ b/changelog.d/3668.misc
@@ -0,0 +1 @@
+Port over enough to Python 3 to allow the sytests to start.
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 022211e34e..6502a6be7b 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -211,7 +211,7 @@ class Auth(object):
             user_agent = request.requestHeaders.getRawHeaders(
                 b"User-Agent",
                 default=[b""]
-            )[0]
+            )[0].decode('ascii', 'surrogateescape')
             if user and access_token and ip_addr:
                 yield self.store.insert_client_ip(
                     user_id=user.to_string(),
@@ -682,7 +682,7 @@ class Auth(object):
         Returns:
             bool: False if no access_token was given, True otherwise.
         """
-        query_params = request.args.get("access_token")
+        query_params = request.args.get(b"access_token")
         auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
         return bool(query_params) or bool(auth_headers)
 
@@ -698,7 +698,7 @@ class Auth(object):
                 401 since some of the old clients depended on auth errors returning
                 403.
         Returns:
-            str: The access_token
+            unicode: The access_token
         Raises:
             AuthError: If there isn't an access_token in the request.
         """
@@ -720,9 +720,9 @@ class Auth(object):
                     "Too many Authorization headers.",
                     errcode=Codes.MISSING_TOKEN,
                 )
-            parts = auth_headers[0].split(" ")
-            if parts[0] == "Bearer" and len(parts) == 2:
-                return parts[1]
+            parts = auth_headers[0].split(b" ")
+            if parts[0] == b"Bearer" and len(parts) == 2:
+                return parts[1].decode('ascii')
             else:
                 raise AuthError(
                     token_not_found_http_status,
@@ -738,7 +738,7 @@ class Auth(object):
                     errcode=Codes.MISSING_TOKEN
                 )
 
-            return query_params[0]
+            return query_params[0].decode('ascii')
 
     @defer.inlineCallbacks
     def check_in_room_or_world_readable(self, room_id, user_id):
diff --git a/synapse/api/ratelimiting.py b/synapse/api/ratelimiting.py
index 06cc8d90b8..3bb5b3da37 100644
--- a/synapse/api/ratelimiting.py
+++ b/synapse/api/ratelimiting.py
@@ -72,7 +72,7 @@ class Ratelimiter(object):
         return allowed, time_allowed
 
     def prune_message_counts(self, time_now_s):
-        for user_id in self.message_counts.keys():
+        for user_id in list(self.message_counts.keys()):
             message_count, time_start, msg_rate_hz = (
                 self.message_counts[user_id]
             )
diff --git a/synapse/config/logger.py b/synapse/config/logger.py
index cfc20dcccf..3f187adfc8 100644
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -168,7 +168,8 @@ def setup_logging(config, use_worker_options=False):
         if log_file:
             # TODO: Customisable file size / backup count
             handler = logging.handlers.RotatingFileHandler(
-                log_file, maxBytes=(1000 * 1000 * 100), backupCount=3
+                log_file, maxBytes=(1000 * 1000 * 100), backupCount=3,
+                encoding='utf8'
             )
 
             def sighup(signum, stack):
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index 69f7085291..a1e4b88e6d 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -29,7 +29,7 @@ def parse_integer(request, name, default=None, required=False):
 
     Args:
         request: the twisted HTTP request.
-        name (str): the name of the query parameter.
+        name (bytes/unicode): the name of the query parameter.
         default (int|None): value to use if the parameter is absent, defaults
             to None.
         required (bool): whether to raise a 400 SynapseError if the
@@ -46,6 +46,10 @@ def parse_integer(request, name, default=None, required=False):
 
 
 def parse_integer_from_args(args, name, default=None, required=False):
+
+    if not isinstance(name, bytes):
+        name = name.encode('ascii')
+
     if name in args:
         try:
             return int(args[name][0])
@@ -65,7 +69,7 @@ def parse_boolean(request, name, default=None, required=False):
 
     Args:
         request: the twisted HTTP request.
-        name (str): the name of the query parameter.
+        name (bytes/unicode): the name of the query parameter.
         default (bool|None): value to use if the parameter is absent, defaults
             to None.
         required (bool): whether to raise a 400 SynapseError if the
@@ -83,11 +87,15 @@ def parse_boolean(request, name, default=None, required=False):
 
 
 def parse_boolean_from_args(args, name, default=None, required=False):
+
+    if not isinstance(name, bytes):
+        name = name.encode('ascii')
+
     if name in args:
         try:
             return {
-                "true": True,
-                "false": False,
+                b"true": True,
+                b"false": False,
             }[args[name][0]]
         except Exception:
             message = (
@@ -104,21 +112,29 @@ def parse_boolean_from_args(args, name, default=None, required=False):
 
 
 def parse_string(request, name, default=None, required=False,
-                 allowed_values=None, param_type="string"):
-    """Parse a string parameter from the request query string.
+                 allowed_values=None, param_type="string", encoding='ascii'):
+    """
+    Parse a string parameter from the request query string.
+
+    If encoding is not None, the content of the query param will be
+    decoded to Unicode using the encoding, otherwise it will be encoded
 
     Args:
         request: the twisted HTTP request.
-        name (str): the name of the query parameter.
-        default (str|None): value to use if the parameter is absent, defaults
-            to None.
+        name (bytes/unicode): the name of the query parameter.
+        default (bytes/unicode|None): value to use if the parameter is absent,
+            defaults to None. Must be bytes if encoding is None.
         required (bool): whether to raise a 400 SynapseError if the
             parameter is absent, defaults to False.
-        allowed_values (list[str]): List of allowed values for the string,
-            or None if any value is allowed, defaults to None
+        allowed_values (list[bytes/unicode]): List of allowed values for the
+            string, or None if any value is allowed, defaults to None. Must be
+            the same type as name, if given.
+        encoding: The encoding to decode the name to, and decode the string
+            content with.
 
     Returns:
-        str|None: A string value or the default.
+        bytes/unicode|None: A string value or the default. Unicode if encoding
+        was given, bytes otherwise.
 
     Raises:
         SynapseError if the parameter is absent and required, or if the
@@ -126,14 +142,22 @@ def parse_string(request, name, default=None, required=False,
             is not one of those allowed values.
     """
     return parse_string_from_args(
-        request.args, name, default, required, allowed_values, param_type,
+        request.args, name, default, required, allowed_values, param_type, encoding
     )
 
 
 def parse_string_from_args(args, name, default=None, required=False,
-                           allowed_values=None, param_type="string"):
+                           allowed_values=None, param_type="string", encoding='ascii'):
+
+    if not isinstance(name, bytes):
+        name = name.encode('ascii')
+
     if name in args:
         value = args[name][0]
+
+        if encoding:
+            value = value.decode(encoding)
+
         if allowed_values is not None and value not in allowed_values:
             message = "Query parameter %r must be one of [%s]" % (
                 name, ", ".join(repr(v) for v in allowed_values)
@@ -146,6 +170,10 @@ def parse_string_from_args(args, name, default=None, required=False,
             message = "Missing %s query parameter %r" % (param_type, name)
             raise SynapseError(400, message, errcode=Codes.MISSING_PARAM)
         else:
+
+            if encoding and isinstance(default, bytes):
+                return default.decode(encoding)
+
             return default
 
 
diff --git a/synapse/http/site.py b/synapse/http/site.py
index f5a8f78406..ad2a98468e 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -235,7 +235,7 @@ class SynapseRequest(Request):
         # need to decode as it could be raw utf-8 bytes
         # from a IDN servname in an auth header
         authenticated_entity = self.authenticated_entity
-        if authenticated_entity is not None:
+        if authenticated_entity is not None and isinstance(authenticated_entity, bytes):
             authenticated_entity = authenticated_entity.decode("utf-8", "replace")
 
         # ...or could be raw utf-8 bytes in the User-Agent header.
@@ -328,7 +328,7 @@ class SynapseSite(Site):
         proxied = config.get("x_forwarded", False)
         self.requestFactory = SynapseRequestFactory(self, proxied)
         self.access_logger = logging.getLogger(logger_name)
-        self.server_version_string = server_version_string
+        self.server_version_string = server_version_string.encode('ascii')
 
     def log(self, request):
         pass
diff --git a/synapse/rest/client/transactions.py b/synapse/rest/client/transactions.py
index 511e96ab00..48c17f1b6d 100644
--- a/synapse/rest/client/transactions.py
+++ b/synapse/rest/client/transactions.py
@@ -53,7 +53,7 @@ class HttpTransactionCache(object):
             str: A transaction key
         """
         token = self.auth.get_access_token_from_request(request)
-        return request.path + "/" + token
+        return request.path.decode('utf8') + "/" + token
 
     def fetch_or_execute_request(self, request, fn, *args, **kwargs):
         """A helper function for fetch_or_execute which extracts
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index 9b22d204a6..c1240e1963 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -55,7 +55,7 @@ class UploadResource(Resource):
         requester = yield self.auth.get_user_by_req(request)
         # TODO: The checks here are a bit late. The content will have
         # already been uploaded to a tmp file at this point
-        content_length = request.getHeader("Content-Length")
+        content_length = request.getHeader(b"Content-Length").decode('ascii')
         if content_length is None:
             raise SynapseError(
                 msg="Request must specify a Content-Length", code=400
@@ -66,10 +66,10 @@ class UploadResource(Resource):
                 code=413,
             )
 
-        upload_name = parse_string(request, "filename")
+        upload_name = parse_string(request, b"filename", encoding=None)
         if upload_name:
             try:
-                upload_name = upload_name.decode('UTF-8')
+                upload_name = upload_name.decode('utf8')
             except UnicodeDecodeError:
                 raise SynapseError(
                     msg="Invalid UTF-8 filename parameter: %r" % (upload_name),
@@ -78,8 +78,8 @@ class UploadResource(Resource):
 
         headers = request.requestHeaders
 
-        if headers.hasHeader("Content-Type"):
-            media_type = headers.getRawHeaders(b"Content-Type")[0]
+        if headers.hasHeader(b"Content-Type"):
+            media_type = headers.getRawHeaders(b"Content-Type")[0].decode('ascii')
         else:
             raise SynapseError(
                 msg="Upload request missing 'Content-Type'",
diff --git a/synapse/secrets.py b/synapse/secrets.py
index f05e9ea535..f6280f951c 100644
--- a/synapse/secrets.py
+++ b/synapse/secrets.py
@@ -38,4 +38,4 @@ else:
             return os.urandom(nbytes)
 
         def token_hex(self, nbytes=32):
-            return binascii.hexlify(self.token_bytes(nbytes))
+            return binascii.hexlify(self.token_bytes(nbytes)).decode('ascii')
diff --git a/synapse/util/logutils.py b/synapse/util/logutils.py
index 62a00189cc..ef31458226 100644
--- a/synapse/util/logutils.py
+++ b/synapse/util/logutils.py
@@ -20,6 +20,8 @@ import time
 from functools import wraps
 from inspect import getcallargs
 
+from six import PY3
+
 _TIME_FUNC_ID = 0
 
 
@@ -28,8 +30,12 @@ def _log_debug_as_f(f, msg, msg_args):
     logger = logging.getLogger(name)
 
     if logger.isEnabledFor(logging.DEBUG):
-        lineno = f.func_code.co_firstlineno
-        pathname = f.func_code.co_filename
+        if PY3:
+            lineno = f.__code__.co_firstlineno
+            pathname = f.__code__.co_filename
+        else:
+            lineno = f.func_code.co_firstlineno
+            pathname = f.func_code.co_filename
 
         record = logging.LogRecord(
             name=name,
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index 43d9db67ec..6f318c6a29 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -16,6 +16,7 @@
 import random
 import string
 
+from six import PY3
 from six.moves import range
 
 _string_with_symbols = (
@@ -34,6 +35,17 @@ def random_string_with_symbols(length):
 
 
 def is_ascii(s):
+
+    if PY3:
+        if isinstance(s, bytes):
+            try:
+                s.decode('ascii').encode('ascii')
+            except UnicodeDecodeError:
+                return False
+            except UnicodeEncodeError:
+                return False
+            return True
+
     try:
         s.encode("ascii")
     except UnicodeEncodeError:
@@ -49,6 +61,9 @@ def to_ascii(s):
 
     If given None then will return None.
     """
+    if PY3:
+        return s
+
     if s is None:
         return None
 
diff --git a/synapse/util/versionstring.py b/synapse/util/versionstring.py
index 1fbcd41115..3baba3225a 100644
--- a/synapse/util/versionstring.py
+++ b/synapse/util/versionstring.py
@@ -30,7 +30,7 @@ def get_version_string(module):
                 ['git', 'rev-parse', '--abbrev-ref', 'HEAD'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
             git_branch = "b=" + git_branch
         except subprocess.CalledProcessError:
             git_branch = ""
@@ -40,7 +40,7 @@ def get_version_string(module):
                 ['git', 'describe', '--exact-match'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
             git_tag = "t=" + git_tag
         except subprocess.CalledProcessError:
             git_tag = ""
@@ -50,7 +50,7 @@ def get_version_string(module):
                 ['git', 'rev-parse', '--short', 'HEAD'],
                 stderr=null,
                 cwd=cwd,
-            ).strip()
+            ).strip().decode('ascii')
         except subprocess.CalledProcessError:
             git_commit = ""
 
@@ -60,7 +60,7 @@ def get_version_string(module):
                 ['git', 'describe', '--dirty=' + dirty_string],
                 stderr=null,
                 cwd=cwd,
-            ).strip().endswith(dirty_string)
+            ).strip().decode('ascii').endswith(dirty_string)
 
             git_dirty = "dirty" if is_dirty else ""
         except subprocess.CalledProcessError:
@@ -77,8 +77,8 @@ def get_version_string(module):
                 "%s (%s)" % (
                     module.__version__, git_version,
                 )
-            ).encode("ascii")
+            )
     except Exception as e:
         logger.info("Failed to check for git repository: %s", e)
 
-    return module.__version__.encode("ascii")
+    return module.__version__