Login fails, no error message

Problem

Login as normal user leads to white page. Apache logs a 500-error, but nothing more. Activating debugging in vtiger ( http://wiki.vtiger.com/index.php/Developer:Debug_techniques ) does nothing.

Login as admin is possible, after session cookie has been deleted.

The problem occured after moving the (mysql) database / webserver installation from Ubuntu to Windows (don’t ask).

Research

Other user have encountered this problem before, it may be a unicode or backup/restore issue - or something braindead like

http://trac.vtiger.com/cgi-bin/trac.cgi/ticket/3719

It is not currently an open bug:

http://trac.vtiger.com/cgi-bin/trac.cgi/report/26

Solution

1. Delete session cookie.
2. Login as admin.
3. Deactivate user account
4. Activate user account

Why this works is beyond me, but it does (for us).

Note: If you get a white screen on edit/update of accounts, you should check if it’s the ExpressionEngine:

PHP Fatal error: Multiple access type modifiers are not allowed in ..\htdocs\vtiger\504\modules\FieldFormulas\expression_engine\VTExpressionEngine.inc on line 160

=> there is “private private function parse($str){” where you should delete one “private”.

(source: http://forum.vtiger.de/viewtopic.php?f=34&t=4888 )