Once I updated EasyApache 3 to EasyApache 4 in cPanel and noticed in the PHP logs the following:
[29-Mar-2018 15:54:45 UTC] PHP Warning: Unknown: open(/var/cpanel/php/sessions/ea-php56/sess_3d96o7nnlnnr473p8619vqkdm1, O_RDWR) failed: Permission denied (13) in Unknown on line 0 [29-Mar-2018 15:54:45 UTC] PHP Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/cpanel/php/sessions/ea-php56) in Unknown on line 0
The warning occurs because PHP can not write session files to a directory to which it does not have access rights.
I looked at the rights of this directory, the group and owner was root, and it was also allowed to write and execute for everyone, except reading.
To resolve this warning, you can open full access for everyone:
chmod 777 /var/cpanel/php/sessions/ea-php56
Or open a PHP configuration, for example in the nano editor:
session.save_path = "/var/cpanel/php/sessions/ea-php56"
And change to:
session.save_path = "/tmp"
That used to be on the old EasyApache3 in the PHP configuration /usr/local/lib/php.ini.
After that, the warning did not appear.