Get 500 Internal Server Error from Prestashop

After transferred Prestashop from one location to another, but unfortunately getting the 500 Internal Server Error?

Just share some tips how I debug it.

A very wise method is go to Apache logs folder to check those error log. For my case it is at /var/log/apache2/. Check the error_log file and immediately, the latest log shows that it has serious issue writing at my prestashop tools/smarty/compile folder.

PHP Fatal error: Smarty error: unable to write to $compile_dir ‘xxx/xxx/tools/smarty/compile’. Be sure $compile_dir is writable by the web server user. in xxx/xxxx/tools/smart/Smarty.class.php on line 1095

So obviously the permission issue, so change it to 777 and immediately it is working again.

Problem resolved.