ALL projects reporting non-existent errors since last upgrade

After installing the latest version (2021.1.2f), I cannot run a single project. EVERY project says there are compiler errors. Even new projects or Unity’s own sample projects. Unity tells me to go into Safe Mode, but there are NO errors listed in the Console. I have tried changing the Version. Tried going in and out of Safe Mode. Rebooted. Even uninstalled/reinstalled Unity. Nothing works! I cannot run a single project. WTF is going on?

Make sure your log console selector buttons are enabled. See this graphic:

https://discussions.unity.com/t/733002/10

https://discussions.unity.com/t/804947/4