Upgrading to mediawiki 1.18
When I was upgrading my wikis to version 1.18, I encountered several problems. I resolved those problems, and to help users who run into the same issues I will document the solution here.
First problem: after upgrading, the URL http://<site>/mw-config/index.php does not work
When you, as per instruction in the UPGRADE readme file, browse to the URL http://<site>/mw-config/index.php, it does not show up.
If you look into the apache error log, you will find entries like
PHP Fatal error: Cannot redeclare wfprofilein() (previously declared in /srv/www/htdocs/wiki/includes/profiler/Profiler.php:14) in /s
rv/www/htdocs/wiki/includes/ProfilerStub.php on line 24 This can be fixed by editing the file 'StartProfiler.php' in your wiki root.