Error after Update to 2.5 (2 replies)

Hi,

I've done the one-click-update. After processing I got this error:
Variable "dimensionsToUpdate" does not exist in "@CoreUpdater/runUpdaterAndExit_welcome.twig" at line 38
There is now no possibility to do anything else, no login, nothing :(
PHP Version 5.5.15


Please give me some advice
Cheers

Timo