Using new Input System spams a UGUI error

I see the following stacktrace every Update:

InvalidOperationException: You are trying to read Input using the UnityEngine.Input class, but you have switched active Input handling to Input System package in Player Settings.
UnityEngine.Input.get_mousePosition () (at <2efdc780086b47f28399fd0ce7a4bfa4>:0)
UnityEngine.UI.MultipleDisplayUtilities.GetMousePositionRelativeToMainDisplayResolution () (at C:/Program Files/Unity/Hub/Editor/2019.3.0f3/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/MultipleDisplayUtilities.cs:40)
UnityEngine.EventSystems.BaseInput.get_mousePosition () (at C:/Program Files/Unity/Hub/Editor/2019.3.0f3/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/InputModules/BaseInput.cs:75)
UnityEngine.EventSystems.StandaloneInputModule.UpdateModule () (at C:/Program Files/Unity/Hub/Editor/2019.3.0f3/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/InputModules/StandaloneInputModule.cs:183)
UnityEngine.EventSystems.EventSystem.TickModules () (at C:/Program Files/Unity/Hub/Editor/2019.3.0f3/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/EventSystem.cs:331)
UnityEngine.EventSystems.EventSystem.Update () (at C:/Program Files/Unity/Hub/Editor/2019.3.0f3/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/EventSystem/EventSystem.cs:344)

I use 2019.3.0f3.

I know of similar issues with URP (https://issuetracker.unity3d.com/is...42.1224778911.1581113660-871491889.1576850238), but I do not use that package.
Does anyone know how to fix this? Or if not, if this is a known problem?

Thank you

Seems this was due to using the old EventSystem in this Scene.