Blank page index.php after Upgrade to 1.3.8a

I installed upgrade from 1.2.4.1 to 1.3.8a successfully.
After restart, I get only white page. I didn´t find anything in the forum.
Who can help me, and which informations are necessary for help?

Hi there - I think I my programmer found the problem and the problem was in the server php.ini file and it is to do with the way the server handles sessions as a default.

We had to change the server php.ini file by tweaking the zc_install/includes/functions/sessions.php file and adding this code to it at the top:

ini_set('session.save_handler','files');

• fortunately the server I am on allowed our modified file to changed the server's php.ini file and this change allowed the install to carry on - basically from what I can gather the server was defaulting to save sessions as 'memcache' and not files so that the install could not find the correct paths?? Not sure I have relayed that back correctly but the fix is what is important. It has now installed perfectly. I hope that helps - I spent hours trolling the forums to no avail and paid someone to find out the issue :(