Plugin not working

Hi, recently my wordpress automatically updated to v. 4.2.4 and I noticed that this plugin wasn’t working.
I have reverted to 4.2.1 and also tried to disable any new plugin I had installed just in case it was a conflict, but to no avail.

Can you please advise on what might be going on?

Thank you in advance for your reply.

Regards

https://www.ads-software.com/plugins/allow-multiple-accounts/