Several users, since the release of php 7.0 are either opening hosting accounts that have php 7.0 already set as default, or switching to php 7.0, and getting errors. Particularly parse errors.
Oxwall has only been approved to run on php 5.5, or 5.6. If you are getting errors, this needs to be the first thing you check to eliminate that as the cause.
You can also check to verify that your server requirements are met by looking at right side of this page. Your hosting provider should be able to assist you with making sure that all of the requirements are met.
https://developers.oxwall.com/hosting