Q:

Extreme case of "Error retrieving parent for item"

My Xamarin Android project doesn't compile anymore, with a couple error messages saying

Error APT0000: Error retrieving parent for item: No resource found that matches the given name 'Widget.Design.TabLayout'

Other errors that were thrown previously were in the same style, but said 

No resource found that matches the given name (at 'textColor' with value '@color/md_white_1000')

I am aware that this is a very common Xamarin bug that is normally fixed by cleaning and rebuilding or, in rare cases, by clearing all packages and package caches so that they are downloaded again. However, this did not fix my error. I also completely reinstalled Xamarin and Visual Studio, but the error persists. At this point, i don't really know what to do except completely reformat my Mac.
Are there any trouble shooting steps I missed? Is this a bug that is only present in some version so that I need to downgrade? Please help, as I haven't been able to compile my code now for two days. 

A:

I found the answer: Apparently the newest version of the Xamarin AppCompat Package is corrupt. I was able to compile again by manually copying the project from my colleague, who hadn't updated his packages (the packages are in our .gitignore). That solved the problem and also explains why clearing the package caches didn't work: Visual Studio simply re-downloaded the corrupt package.

