Error in upgrade11.1.100.0 to 11.2.300.0

I have upgraded our site to 11.2.300.0 but when I try to run either Kinetic or Modern I get an error message.

I have turned off windows defender and the virus software on the server and still get the error. I am trying to work thru this with Epicor support but they keep saying its firewall related.

Anyone have this issue before?