Hi Cliff,
We would recommend setting the following permissions:
sudo chown -R www-data:www-data .
sudo chmod -R 755 .
sudo chmod -R 775 cache custom modules themes data upload config_override.php
You may need to turn on error reporting to debug the issue, to do this simply set ini_set(‘display_errors’,1); at the start of the index.php file. We would advise removing this as soon as it is no longer required, to prevent errors outputting throughout the CRM.
Thanks,
Will.