In addition to what was proposed by william-ivanski with pinning and packages from Xamarin repository as a workaround, you need to downgrade with: # sudo apt install monodevelop=5.10.0.871-0xamarin2
In addition to what was proposed by william-ivanski with pinning and packages from Xamarin repository as a workaround, you need to downgrade with: 5.10.0. 871-0xamarin2
# sudo apt install monodevelop=