--- a/mercurial/hgweb/webutil.py	Sat Feb 17 01:09:56 2018 -0500
+++ b/mercurial/hgweb/webutil.py	Sat Feb 17 01:11:48 2018 -0500
@@ -347,7 +347,7 @@
     try:
         return util.processlinerange(fromline, toline)
     except error.ParseError as exc:
-        raise ErrorResponse(HTTP_BAD_REQUEST, str(exc))
+        raise ErrorResponse(HTTP_BAD_REQUEST, pycompat.bytestr(exc))
 
 def formatlinerange(fromline, toline):
     return '%d:%d' % (fromline + 1, toline)