Sometimes we came across the following error when try to access phpmyadmin from cpanel.
Access Denied Unable to establish a PHP session. If you believe that this is in error or inadvertent, contact your system administrator and ask them to review your server settings.
Usually this error occurs when the permission or ownership of the tmp folder for the user is wrong. So make sure the ownership of /home/$username/tmp folder has ownership set to $user and permission as 755. If it is not, you will face the same error.
1. SSH into the server as root.
2. Check the permission and ownership of /home/$user/tmp folder. Set ownership as $user
chown $user. /home/$user/tmp
3. Set permission of the tmp folder to 755.
chmod 755 /home/$user/tmp