Sometimes, it happens that when you try to access your domain in a web browser you will get a 500 Internal Server Error and after checking all the permissions and ownerships for all files and folders under that domain you will find that everything is correct but still getting that error in the browser.
But when you try to manually execute the php file from the server using the php command, you will get below error.
File size limit exceeded
The reason for that error is that one of the file probably a log file under that domain exceeds to 2 GB and by default Apache has setting enabled, to display 500 Internal Server Error if in case any file under a domain
You can find the files that are having huge size by issuing below command.
find ./ -size +100M
The issue will be resolved by clearing the log file.