Going to cgi-bin/koha/errors/404.pl in staff side and then clicking the Help and after that clicking Add help you get the following warning/error: edithelp.pl: Use of uninitialized value $lang in concatenation (.) or string at kohaclone/edithelp.pl line 74. The problem is the same type as it is in Bug 14580.
*** This bug has been marked as a duplicate of bug 14580 ***