If you want to know Avast Antivirus Won’t Open you can follow the step given below:
1. Open Avast User Interface > Settings > Troubleshooting, and remove tickmark for ‘Enable Avast self-defence module’ and click ‘OK’.
2. Now open the Task Manager, and kill the instup.exe process if running, if it’s not running, go to step 4.
3. Immediately a pop up appears and informs to update virus definitions as the last attempt was unsuccessful, ignore it, now uninstall Avast, it will, without any issues.
4. You can uninstall Avast, you won’t get that error.
Hopefully, the above steps will help you to fix the issue if not you can also follow our blog to see more on if your avast antivirus will not open.