[Solved] cloudpanel stuck "loading" users list

Last week we’ve upgrade to the latest version of Cloudpanel, but today, we are facing a new issue.

I can log on to the cloudpanel, navigate through company’s, security groups etc, however, when trying to load the users list, it gets stuck and states: “Loading”

I’ve tried adding a new user, which the system succesfully did, but after adding, the users list still isn’t showing.

What could be causing this?

Please advise

Bert