Recently, we deployed a project that was using a multiple file uploader Flash component (that we used before for other projects successfully). To our surprise, it behaved abnormally and, in brief, it could be described as the following:

Every time a flash component was used to upload files it would drop the session (in IE 6 & 7) and consequently log out an already logged in user.

After making sure that all session related code was OK we started digging further - server configuration. Eventually, we narrowed down the cause of the problem and without hesitation annihilated the bugger.

It was Suhosin PHP module that dedicated servers with CPanel usually have installed for maintaining their security. Since it was the first project on this server to use flash uploader (and other servers have different configuration) it was the first time when we experienced the session issue.

Now…to cut story short and to give you what you actually want from the article…

The fix that did the trick was as follows:

1. disable suhosin.session.cryptua setting in php.ini

   suhosin.session.cryptua = Off

2. Add the following (if not there already) to php.ini

   suhosin.session.encrypt = Off

3. Restart apache

   We use CentOS: service httpd restart