Error

Hello all!!!

I am facing a problem in any plugin, theme, or even in the proper WP.
It began a couple of days ago.
the error appears anywhere.

Warning: Unknown: open(/var/lib/php/session/sess_9r5k3qmoiqfhed9fbjl36rfer1, O_RDWR) failed: Permission denied (13) in Unknown on line 0

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

This is the error. Appears even in admins page. Can anybody help?

Thanks a lot in advice.

The page I need help with: [log in to see the link]