diff --git a/kallithea/lib/exceptions.py b/kallithea/lib/exceptions.py
--- a/kallithea/lib/exceptions.py
+++ b/kallithea/lib/exceptions.py
@@ -27,6 +27,8 @@ Original author and date, and relevant c
 
 from webob.exc import HTTPClientError
 
+from kallithea.lib.utils2 import safe_str
+
 
 class LdapUsernameError(Exception):
     pass
@@ -86,8 +88,8 @@ class HTTPLockedRC(HTTPClientError):
         from kallithea.lib.utils2 import safe_int
         _code = CONFIG.get('lock_ret_code')
         self.code = safe_int(_code, self.code)
-        self.title = self.explanation = ('Repository `%s` locked by '
-                                         'user `%s`' % (reponame, username))
+        self.title = self.explanation = safe_str(
+            'Repository `%s` locked by user `%s`' % (reponame, username))
         super(HTTPLockedRC, self).__init__(*args, **kwargs)