My 2021 won't open but I don't receive any error message- it just pops up the first window for about 8 seconds but closes without brining up the sign in page.  Just that.  Very strange, but at least happy to know this is a new issue which could take half an eternity to solve, if it can be solved.   I've learned to lose hope right away with Intuit, this lessens the pain from having one's hopes blown to bits.