WHM Account Isolation: What to Check on a Shared Hosting Server

On a shared hosting server, account isolation is a combination of ownership, PHP execution, filesystem permissions, and service configuration. A directory being writable is not enough if the wrong account owns it.

Check that each hosting account's files are owned by the expected cPanel user. Avoid running application commands as root inside customer directories unless necessary; generated cache files can become unreadable to the PHP account. Use the account's configured PHP binary and execution context when clearing Laravel or framework caches.

Review PHP-FPM pool configuration, document roots, symbolic links, and writable directories. The web process should have write access only where the application requires it, such as cache, sessions, logs, and uploaded files. Avoid broad permissions such as 777 as a shortcut.

When a site returns a 500 error, inspect the application log and the relevant web-server or PHP-FPM log before recursively changing permissions. Correct the specific ownership or mode problem, then verify the site and confirm no unrelated accounts were affected.