7 – PHP content cannot be created or modified in D7 sites after ISP migration

I recently migrated my D7 websites to A2 Hosting. Everything was working fine, until I had to edit a node which had some simple PHP code content in its body (it only shows different links if the user is anonymous or authenticated).

After modifying the content and clicking on ‘Save’, the page reloads, not giving any message (such as ‘node was updated’), showing the content editing form as it was prior to the editing.

If I try to create a new page whose body is formated as PHP code, the page is reloaded with a blank form after I hit ‘Save’.

Despite this, all my previous, unmodified PHP snippets were working fine.

This happens in 3 D7 websites I have hosted at A2. In one of them, as an attempt to fix the issue, I tried to turn PHP filter module temporarily OFF to turn it ON again afterwards. I managed to turn it OFF, but could never turn it back ON. If I switch the ON key beside PHP filter module, click on ‘Save configuration’, the page reloads without any messages, and the module remains OFF. Now every PHP content and blocks stopped working in that site.

What could be the problem?