Looks like I'm not alone in this mess. Clicked to open illustrator 2021 this morning, and the indicator arrow shows below app icon but the program doesn't load. It is also highlighted in red in the force quit box. It started running diagnostics and recommended me do something with extensions, so I figured I'd just uninstall and reinstall. As I'm uninstalling, it just says "waiting" in the creative cloud box. Fortunately I have Time Machine working so I could grab the 2020 version I uninstalled a couple days ago.
Sorry to hear about your experience. I would request if you could share the crash report by following these steps ( https://helpx.adobe.com/in/illustrator/kb/crash-next-steps.html ).
While submitting the crash report please use the same email address, with which you are signed in on this community. This will help us find the crash report and help accordingly.
Once done, please try steps suggested on this page (https://community.adobe.com/t5/illustrator/how-to-fix-a-crash-and-recover-documents-in-illustrator/t...) and let us know if it helps.
Illustrator keeps crashing..... now won't open ....
Have huge presentation tomorrow - freaking out!!! Not had this issue for about 10 years!!
Can anyone help?