One of my External Commands is failing and the error msg doesn't say much, if not this
Revit encountered a System.TypeLoadException: Could not load type 'System.ValueTuple`3' from assembly 'System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f.....'.
at MyAppNamespace.MyButton.Execute(ExternalCommandData commandData, ...
What am I doing wrong ?
