diff --git a/rhodecode/apps/ssh_support/lib/backends/svn.py b/rhodecode/apps/ssh_support/lib/backends/svn.py
--- a/rhodecode/apps/ssh_support/lib/backends/svn.py
+++ b/rhodecode/apps/ssh_support/lib/backends/svn.py
@@ -25,6 +25,8 @@ import tempfile
 from subprocess import Popen, PIPE
 import urllib.parse
 
+from rhodecode.lib.str_utils import safe_bytes
+from rhodecode_tools.lib.utils import safe_str
 from .base import SshVcsServer
 
 log = logging.getLogger(__name__)
@@ -81,7 +83,7 @@ class SubversionTunnelWrapper(object):
 
     def sync(self):
         while self.process.poll() is None:
-            next_byte = self.stdin.read(1)
+            next_byte = self.stdin.buffer.read(1)
             if not next_byte:
                 break
             self.process.stdin.write(next_byte)
@@ -106,7 +108,7 @@ class SubversionTunnelWrapper(object):
         data['url'] = self._svn_string(data['url'])
         data['ra_client'] = self._svn_string(data['ra_client'])
         data['client'] = data['client'] or ''
-        buffer_ = (
+        buffer_ = safe_bytes(
             "( {version} ( {capabilities} ) {url}{ra_client}"
             "( {client}) ) ".format(**data))
         self.process.stdin.write(buffer_)
@@ -127,21 +129,21 @@ class SubversionTunnelWrapper(object):
         return f'{len(str_)}:{str_} '
 
     def _read_first_client_response(self):
-        buffer_ = ""
+        buffer_ = b""
         brackets_stack = []
         while True:
-            next_byte = self.stdin.read(1)
+            next_byte = self.stdin.buffer.read(1)
             buffer_ += next_byte
-            if next_byte == "(":
+            if next_byte == b"(":
                 brackets_stack.append(next_byte)
-            elif next_byte == ")":
+            elif next_byte == b")":
                 brackets_stack.pop()
-            elif next_byte == " " and not brackets_stack:
+            elif next_byte == b" " and not brackets_stack:
                 break
 
         return buffer_
 
-    def _parse_first_client_response(self, buffer_):
+    def _parse_first_client_response(self, buffer_: bytes):
         """
         According to the Subversion RA protocol, the first request
         should look like:
@@ -151,16 +153,20 @@ class SubversionTunnelWrapper(object):
 
         Please check https://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_ra_svn/protocol
         """
-        version_re = r'(?P<version>\d+)'
-        capabilities_re = r'\(\s(?P<capabilities>[\w\d\-\ ]+)\s\)'
-        url_re = r'\d+\:(?P<url>[\W\w]+)'
-        ra_client_re = r'(\d+\:(?P<ra_client>[\W\w]+)\s)'
-        client_re = r'(\d+\:(?P<client>[\W\w]+)\s)*'
+        version_re = br'(?P<version>\d+)'
+        capabilities_re = br'\(\s(?P<capabilities>[\w\d\-\ ]+)\s\)'
+        url_re = br'\d+\:(?P<url>[\W\w]+)'
+        ra_client_re = br'(\d+\:(?P<ra_client>[\W\w]+)\s)'
+        client_re = br'(\d+\:(?P<client>[\W\w]+)\s)*'
         regex = re.compile(
-            r'^\(\s{version}\s{capabilities}\s{url}\s{ra_client}'
-            r'\(\s{client}\)\s\)\s*$'.format(
-                version=version_re, capabilities=capabilities_re,
-                url=url_re, ra_client=ra_client_re, client=client_re))
+            br'^\(\s%b\s%b\s%b\s%b'
+            br'\(\s%b\)\s\)\s*$' % (
+                version_re,
+                capabilities_re,
+                url_re,
+                ra_client_re,
+                client_re)
+        )
         matcher = regex.match(buffer_)
 
         return matcher.groupdict() if matcher else None
@@ -202,7 +208,7 @@ class SubversionTunnelWrapper(object):
 
         url_parts = urllib.parse.urlparse(first_response['url'])
 
-        self.server.repo_name = self._match_repo_name(url_parts.path.strip('/'))
+        self.server.repo_name = self._match_repo_name(safe_str(url_parts.path).strip('/'))
 
         exit_code = self.server._check_permissions(action)
         if exit_code: