I just ran into an unexpected issue when I was trying to update code for a project. When I had previously closed the IDE yesterday I had the Serial Monitor open. Today when I opened the code in a fresh instance of the IDE it got stuck trying to download the first package_index.json that I have in my Additional Boards Manager URLs.
I discovered that it is possibly a known issue with the IDE - Exceptionally long duration of "Downloading index: .... What fixed it for me was closing the Serial Monitor and reopening it after the IDE finished startup. I am using IDE version 2.3.3 and there isn't any released update available so I guess the problem is not fixed yet.
Just thought I'd mention it here as it surprised me because I hadn't updated either the code or IDE and would never have expected an interaction with the Serial Monitor. Maybe I'll just remember to close it when I shutdown.
