I'be been using the Arduino IDE on this computer for years with no issues. I always kept the version updated to the newest. Today I updated to the latest version 2.0.4 and now whenever I open the IDE I get an error message "Ignoring sketch with bad name" as the titles and the message conveys sketch name conventions.
The issue is that my sketch names have never changed. I have used spaces in many sketch names with absolutely no problems.
I uninstalled it and reinstalled my older version and I get the same thing.
Why would it suddenly complain about naming conventions?