Session files writing error

[Somebody1]

For only one vhost, I get this error:

PHP message: PHP Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/lib/php/session) in Unknown on line 0" while reading upstream, client: IP-REMOVED, server: website.com, request: "GET /contact/ HTTP/1.1", upstream: "fastcgi://unix:/var/www/vhosts/system/website.com/php-fpm.sock:", host: "website.com", referrer: "http://website.com/"

I'm using CloudLinux 6.5 and Plesk 12.0.18. The strangest thing is: it's only one vhost causing this problem. All other vhosts have the same configuration (nginx processing PHP), and are working fine. When setting the webserver to apache, the problem disappears...

Edit: When disabling CageFS for the specific website, the error disappears. Change it back, and it pops up again. All others in CageFS are working fine...

Edit2: Seems I am wrong. Now also other vhosts reproduce the same error. Disabling CageFS solves it. This seems to be a bug. Manually creating var/lib/php/session within .cagefs doesn't help neither...

 

[IgorG]

Please note that cagefs is a third party application which is not officially tested with Plesk, hence we can not guarantee its proper functionality along with Plesk.
As far as I know php.ini configuration loading from different location (behind cageFS) but not from default Plesk location and it is causing the issue. So, you need to use Plesk vhosts php.ini but not cageFS php.ini.