Hi John,
I just upgraded to 7.5 and changed to PHP 7.0 at the same time. I also ran into the same error as LukeDoaglas, deleting "enomnewtlds" fixed that particular error for me too. But there is a different error now blocking me from seeing any invoices:
Whoops\Exception\ErrorException: The file /home/xxxx/public_html/whmcs/modules/gateways/payoffline.php was encoded by the ionCube Encoder for PHP 5.0 and cannot run under PHP 7.0.
Any ideas what I should do? I'm currently blocked from viewing or creating any invoices...
Thanks,
Jamie