thank you very much for your response!
Dynamo Core 22.214.171.12426
Dynamo Civil 3D 126.96.36.1997
13.2.1758.0 Civil 3D 2020.2 Update
In Manage next to Dynamo I have “Run Script” - not dynamo player like in Revit. If I hit that and select the scrypt, no extra window will open but it says scrypt is running successfully. No warning or fatal error. I used one sample scrypt (Civil3D_SplitCorridorSolid) and it did not work, but I got no warning. Maybe it did not work because I need to work on the scrypt and change more then just the name of the corridor. A very simple Scrypt I created - Line by coordinates, worked fine. Could also save the file, without fatal error (which was the case before).
I can launch Dynamo with that command. Launching was never an issue. I can work on dynamo but when I hit run I get the warning I showed in my first post.
Please let me know if you need additional informations.