500 Server Error when installing/upgrading Membership plugin


I am trying to test out the latest version of the Membership plugin on my development site. I tried the automatic upgrade button but it said it had failed.

So I deleted the old plugin files via FTP and then installed the latest version via the wpmu dev dashboard.

There is now a 500 server error on all of the Membership plugin pages in the wordpress dashboard. The other pages in the wp admin are fine. It’s just the plugin pages.

Do you know what could have gone wrong please?

Many Thanks