Unit testing on ArcGIS Pro 2.8 Add-In throws error: Unable to load ArcGIS.DeskTop.Framework.

[BobTaylor]

After upgrading ArcGIS Pro from 2.7.3 to 2.8.0 my unit test are now failing with an unable to load ArcGIS.DeskTop.Framework error when it tries to load the assembly for ArcGIS.Desktop.Framework.Threading.Tasks. My class constructor creates a CancelableProgressorSource object. This worked fine in 2.7. Any suggestions? 

[CharlesMacleod · Accepted solution]

I think this might be related to this problem: https://support.esri.com/en/Technical-Article/000025544 

can u check your build setting and make sure it is x64 (and not AnyCPU)

[BobTaylor]

Yes, my build setting is AnyCPU. I'll try setting it to x64 and see if it resolves the issue. Thanks for the reply.