After takeoff above FL 180 I get a Diff Pressure Warning. I “Dumped” the cabin Pressure. Then it changed to Cabin Altitude Warning. I don’t know how to alleviate this issue. It just started happening a couple days ago.
Check out this thread. The fix for me (and many others) has been to upgrade to the latest WT G3000 and get the latest version of Dakfly’s Longitude mod (which I think is 1.90a).