I installed the compatibility patch. The error message comes up in lobby, I click yes, then it says it was successful, I click yes, and the cycle continues.

Hi.

Please browse to : C:\Program Files (x86)\Steam\steamapps\common\Age2HD\ and check if there is a folder called "New folder" . If there is, enter into it, copy all files inside of it, go back to C:\Program Files (x86)\Steam\steamapps\common\Age2HD\ and paste.

Run the game diagnostics again and check.

If it still doesn't work, you can download manually the compatibility patch here : [You must login to view link] and install it.