I have faced with issue while opening Avantfax web page but it can be consequence of installing httpd update:
Warning: Unknown: open(/tmp/sess_3ec229c4cb7b053749c6f68d047aa95a, 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 () in Unknown on line 0
it works when i add in index php:
ini_set('session.save_path',getcwd(). '/tmp');