Likely requires a complete uninstall of 2.0.3 and perhaps other dynamo components. Check the registry before reinstalling to ensure it’s in a stable state.
I uninstalled from control panel all versions of Dynamo, also ran microsoftprogram_installandUninstall.meta and cleared the c drive program files dynamo folder and program data folders.
Then reinstalled Dynamo for Revit 2.01 and then updated to Dynamo for Revit 2.03 and all ok. Do not have dynamo in Revit 2016 anymore but not stressed about that.
Thank you to the quick reply and apology for my slow response