Common failures.
BLANK PAGE OR SERVER ERROR
Read the log first, then the server error log.
Debug mode is off in production, so the browser shows nothing useful.
WHERE THE LOG IS
The storage logs directory.
PERMISSION ERRORS
Storage is not writable. The error names the path.
CONFIGURATION CHANGES NOT TAKING EFFECT
Configuration is cached. Rebuild it.
That is the most common report.
DATABASE ACCESS DENIED
Names missing the cPanel prefix, or privileges not granted.
MISSING CLASS OR DEPENDENCY
Dependencies not installed, or installed with a different PHP version.
ROUTES RETURNING NOT FOUND
The rewrite rules are missing, or the public directory arrangement is wrong.
ASSETS NOT LOADING
Public files not in the served directory, or the application address is wrong.
STORAGE FILES NOT ACCESSIBLE
The storage link is missing after deployment.
SCHEDULED TASKS NOT RUNNING
Cron entry missing, wrong PHP path, or wrong application path.
MAIL NOT SENDING
Credentials, or queued mail with no worker running.
WHAT TO INCLUDE IN A TICKET
The domain, the exact log entry, and what you have checked.