It has compiled without any problems using V2.3.3 several times this morning. Now it will not compile. I see a message Downloading index: package_adafruit_index.json. I have waited over 30 minutes, and the message remains without compiling!!!
It's back
I just uploaded a sketch just fine but now I am getting the Downloading index: package_adafruit_index.json message again and does not compile.
I assume the connection to Adafruit is bad. Enter the IDE Library Manager, type "adafruit" and click "remove" for any Adafruit library you have. Maybe Adafruit has something not up-to-date on their system and your anti-malware is dropping the connection (specifically to Adafruit).