php return 500 error but no error log
If you still have 500 error and no logs you can try to execute from command line:
php -f file.php
it will not work exactly like in a browser (from server) but if there is syntax error in your code, you will see error message in console.
Scan your source files to find @
.
From php documentation site
Currently the "@" error-control operator prefix will even disable error reporting for critical errors that will terminate script execution. Among other things, this means that if you use "@" to suppress errors from a certain function and either it isn't available or has been mistyped, the script will die right there with no indication as to why.