Xamarin android references not found

Question

I am trying to open an existing xamarin project for android, and all the references have exclamation marks.

The properties of the project are to compile for Android 9.0 sdk and this is set to automatically download and install.

I get hundreds of errors and even get 'The type or namespace name 'System' could not be found'

I already looked around on the internet and the only accepted solution was to reinstall windows/visual studio. Surely this cannot be right.

Thanks for any insights.

Answer 1

Thanks for the replies!

Finally as Jack Hua suggested I had to use update-package-reinstall to reinstall all the packages.

One package however blocked this operation, and I had to choose a different TargetFrameworkProfile in the project settings.