I am getting an error when users registered

When users try to register on Joomla site they are seeing the following message: Empty solution not allowed.

The registration is taking them to the Joomdle registration rather than Joomla registration page? Not sure if that has something to do with it?

I am not quite sure what you mean by the Joomdle registration as Joomdle does not have a registration page. Do you have a screen shot you can post?

Do you have green ticks for all items under your system health check?

Yes, I have all green checks. Attached is screen shot before user tries to register and after.

I'm sorry, you can disregard this message. Somehow the k2 plugins were enabled and that is what it was trying to use. Thanks for your prompt service!