I have Mediawiki installation went from 1.17 through 1.18 RC1 and to 1.18
But another Mediawiki has had some problems going direct from 1.17 to 1.18
I took out Recaptcha and now see this:
*Fatal error*: Cannot redeclare wfprofilein() (previously declared in /xxxxxxxx/public_html/includes/profiler/Profiler.php:14) in */xxxxx/public_html/includes/ProfilerStub.php* on line *25*
Gordo