Undefined variable: optionalUserInfo after Update to 2.0.1 (1 reply)

Hi, after I updated to 2.0.1 I got the following error:

There is an error. Please report the message (Piwik 2.0.1) and full backtrace in the Piwik forums (please do a Search first as it might have been reported already!).

Notice: Undefined variable: optionalUserInfo in /www/sbg/tracking/htdocs/core/Filechecks.php on line 97 

Backtrace -->

#0 Piwik\Error::errorHandler(...) called at [/www/sbg/tracking/htdocs/core/Filechecks.php:97]
#1 Piwik\Filechecks::dieIfDirectoriesNotWritable(...) called at [/www/sbg/tracking/htdocs/core/FrontController.php:307]
#2 Piwik\FrontController->init(...) called at [/www/sbg/tracking/htdocs/index.php:70]

Follwing trooubleshout I tried:
Removed all Files from installation, copied all Files from latest.zip to the folder and tried to access the server. but nothing!