HTTP Error 500
Internal Server Error.

click here for what caused this error
Important notice : If this new install with secure server ( https:// ), so this error caused because you removed secure port ( :443 ), you should leave it in installation proccess then importantly remove it after installation proccess is completed from include/config.php file .
Now if you see this error for this reason you can return to installation from the start and complete it without ( :443 ), and it will not happen again, because it happen one time only .
if it is old installation then check reasons above .