TYPO3 7.6 LTS returns security token validation error almost everytime
I'm not sure, but I think I found a bug in the latest 7.6 LTS with my server configuration, so my fresh installations (without any extensions) are unable to interact in the backend. Almost everytime I try to submit a backend form, I get an error because of security token. I tried to fix it with following methods but it takes no affect:
- Reinstall that instance
- (Re-)Login and
out Fix "max_input_vars" in php to "5000"
- Clear all caches
I will be able to give root access to that, so someone could get direct view if desired. See picture for details of that error.
Interesting notices: No PHP or access errors are logged - same in ../typo3temp/logs. Not any kind of feedback neither in the ui nor in the typo3 logs. No errors in the install tool.Is there anybody from CoreDev who can help me?
Webserver Apache/2.4.10 (Debian)
PHP Version 5.6.14-0+deb8u1
Application Context Production
Operating System Linux 3.16.0-4-amd64