When I try to install a new expansion pack/stuff pack from Origin, I get the following error:
DLC Compatibility Alert
It seems the base game for this DLC was not installed through Origin. For
to work, you will first need to:
Select Uninstall Now below, locate the base game, and follow the on-screen instructions to uninstall it.
Download and install the base game through Origin by selecting it in My Games and clicking Download.
After that you can download and play