16 identical Mecanim Animator errors....why?

I’ve no idea why I’m getting these errors when I run my project…

NullReferenceException: (null)
UnityEditor.SerializedObject..ctor (UnityEngine.Object obj) (at C:/BuildAgent/work/d3d49558e4d408f4/artifacts/EditorGenerated/SerializedPropertyBindings.cs:63)
UnityEditor.Graphs.AnimationStateMachine.TransitionInspector.SetTransitionToInspect (UnityEditorInternal.Transition transition) (at C:/BuildAgent/work/d3d49558e4d408f4/Editor/Graphs/UnityEditor.Graphs/AnimationStateMachine/TransitionInspector.cs:173)
UnityEditor.Graphs.AnimationStateMachine.TransitionInspector.OnEnable () (at C:/BuildAgent/work/d3d49558e4d408f4/Editor/Graphs/UnityEditor.Graphs/AnimationStateMachine/TransitionInspector.cs:96)

Does anyone know what it means, or how to get rid of it?
My Animation Controller is simple (so far) with 5 animations - each direction and idle. I don’t want to complicate things until I know what these errors are.

restarting unity worked for me

I have exactly the same problem, have you discovered how to solve?