Tuleap / your request does not appear to be valid

Question

I cannot log into tuleap. Error message « your request does not seem to be valid ».

Tuleap version :10.3.99.48

Already tried: Tuleap —clear-caches Delete firefox cache Restart service/machine Check server fqdn in local.inc Set selinux mode on disabled or permissive

Irm behind a reverse Proxy (Nginx). Which send error messages :

Php message : php warning : unknown failed to write session data(file). Please verify that the current setting of session.save_path is correct (/var/tmp/tuleap_cache//php/session).

Is there a specific setting to set for session.save_path in any php or tuleap conf file? Or something else for the login web page to work?

Thank you