Problem on Unity 2020 and Firebase (Unable to resolve reference 'UnityEditor.iOS.Extensions.Xcode')

Question

I upgrade my app for Android on Unity 2019.12 to 2020.1. With Unity 2019, Firebase work fine. But with Unity 2020, i have 2 errors. I not use IOS, just Android. How to resolve this ? Thanks.

Assembly 'Assets/Firebase/Editor/Firebase.Editor.dll' will not be loaded due to errors:
Unable to resolve reference 'UnityEditor.iOS.Extensions.Xcode'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.

Assembly 'Assets/PlayServicesResolver/Editor/Google.IOSResolver_v1.2.135.0.dll' will not be loaded due to errors:
Unable to resolve reference 'UnityEditor.iOS.Extensions.Xcode'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.

Answer 1

I ran into this issue by having built the project with iOS Build Support enabled, and then loading the project with a new version of Unity (2020), with iOS Build Support disabled.

Adding iOS build support to the install solved the missing dependency issues.