SessionHandler::write() failed: session.save_path and alt-php on cPanel/CloudLinux

If you are a system administrator and have encountered the following error in your PHP logs:

PHP Warning: SessionHandler::write(): open(/var/cpanel/php/sessions/alt-php74/sess_ecc8f1037c9adc71a4c2a75064937e24, O_RDWR) failed: No such file or directory (2) in /home/user/public_html/vendor/symfony/symfony/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/StrictSessionHandler.php on line 64

PHP Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/cpanel/php/sessions/alt-php74) in /home/user/public_html/vendor/symfony/symfony/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php on line 266

You are not alone. This error occurs when PHP cannot write to the directory that session.save_path points at: a /var/cpanel/php/sessions/alt-phpXX path (alt-php56, alt-php74, alt-php81...) that does not exist on the server. It is almost always caused by the CloudLinux PHP Selector, which sets that path but does not always create the directory.

Here, we explain how to fix this issue in a cPanel environment with CloudLinux 8, cPanel, and CageFS.

Step 1: Verify the existence of directories

First, make sure that the directories mentioned in the error exist. In this case, the directory is /var/cpanel/php/sessions/alt-php74. To create them, use the following commands (I include all versions from PHP 4.4 to PHP 8.3):

mkdir -p /var/cpanel/php/sessions/alt-php44
mkdir -p /var/cpanel/php/sessions/alt-php51
mkdir -p /var/cpanel/php/sessions/alt-php52
mkdir -p /var/cpanel/php/sessions/alt-php53
mkdir -p /var/cpanel/php/sessions/alt-php54
mkdir -p /var/cpanel/php/sessions/alt-php55
mkdir -p /var/cpanel/php/sessions/alt-php56
mkdir -p /var/cpanel/php/sessions/alt-php70
mkdir -p /var/cpanel/php/sessions/alt-php71
mkdir -p /var/cpanel/php/sessions/alt-php72
mkdir -p /var/cpanel/php/sessions/alt-php73
mkdir -p /var/cpanel/php/sessions/alt-php74
mkdir -p /var/cpanel/php/sessions/alt-php80
mkdir -p /var/cpanel/php/sessions/alt-php81
mkdir -p /var/cpanel/php/sessions/alt-php82
mkdir -p /var/cpanel/php/sessions/alt-php83

chmod 1777 /var/cpanel/php/sessions/alt-php44
chmod 1777 /var/cpanel/php/sessions/alt-php51
chmod 1777 /var/cpanel/php/sessions/alt-php52
chmod 1777 /var/cpanel/php/sessions/alt-php53
chmod 1777 /var/cpanel/php/sessions/alt-php54
chmod 1777 /var/cpanel/php/sessions/alt-php55
chmod 1777 /var/cpanel/php/sessions/alt-php56
chmod 1777 /var/cpanel/php/sessions/alt-php70
chmod 1777 /var/cpanel/php/sessions/alt-php71
chmod 1777 /var/cpanel/php/sessions/alt-php72
chmod 1777 /var/cpanel/php/sessions/alt-php73
chmod 1777 /var/cpanel/php/sessions/alt-php74
chmod 1777 /var/cpanel/php/sessions/alt-php80
chmod 1777 /var/cpanel/php/sessions/alt-php81
chmod 1777 /var/cpanel/php/sessions/alt-php82
chmod 1777 /var/cpanel/php/sessions/alt-php83

Step 2: Edit the cagefs.mp file

Add the following lines to the end of your /etc/cagefs/cagefs.mp file so that CageFS includes these directories in its environment:

@/var/cpanel/php/sessions/alt-php44,700
@/var/cpanel/php/sessions/alt-php51,700
@/var/cpanel/php/sessions/alt-php52,700
@/var/cpanel/php/sessions/alt-php53,700
@/var/cpanel/php/sessions/alt-php54,700
@/var/cpanel/php/sessions/alt-php55,700
@/var/cpanel/php/sessions/alt-php56,700
@/var/cpanel/php/sessions/alt-php70,700
@/var/cpanel/php/sessions/alt-php71,700
@/var/cpanel/php/sessions/alt-php72,700
@/var/cpanel/php/sessions/alt-php73,700
@/var/cpanel/php/sessions/alt-php74,700
@/var/cpanel/php/sessions/alt-php80,700
@/var/cpanel/php/sessions/alt-php81,700
@/var/cpanel/php/sessions/alt-php82,700
@/var/cpanel/php/sessions/alt-php83,700

 

Step 3: Update and remount CageFS

After editing cagefs.mp, you need to rebuild and update CageFS for the changes to take effect:

cagefsctl --force-update
cagefsctl --update
cagefsctl --remount-all

Step 4: Verify the changes

To make sure the changes have been applied correctly, you can enter the CageFS environment of a specific user and verify that the directories are present:

cagefsctl --enter <username>
ls /var/cpanel/php/sessions/

Replace with the username to verify that the new directories are present.

Conclusion

By following these steps, you should have resolved the PHP session writing issue within a cPanel environment with CloudLinux 8 and CageFS. Ensure that the session directories exist and are correctly configured in cagefs.mp, and always rebuild and update CageFS after making configuration changes.

We hope this guide has been helpful in resolving the issue and that other system administrators can easily find this solution. Good luck!

If you manage CloudLinux servers, you may also want to read how to fix the kernel problem when updating CloudLinux and how to migrate email accounts to IMAP with imapsync.