session save path is not writable

Problem

If you cannot log in or products are not stored in the shopping cart or get errors in the log like 'session_start failed', 'Failed to write session data', 'save_path is not writable', 'Invalid token session. Please login again'.

Solution

Session_save_path is a PHP variable that is set in php.ini, and on many shared hosting setups, it’s actually set to a location that’s not writable.

Contact your host to solve this.