Cant Apply Config

Good day,

I have upgraded to 2.10RC by installing from command line ./install_amp. after the upgrade, I cannot “Apply Config”. I receive the following error message:

"Error: Did not receive valid response from server

XHR response code: 200 XHR responseText: undefined jQuery status: parsererror"

What might be the issue?

We are facing a lot of problems after the latest upgrade and this is one of them.
The system is completely down!


For those who run into a similar problem here is the solution: