Hi all.
You can try one of this 2 possible options:
1.- Go to Control Panel, Administrative tools, Task Scheduler, Library, Task scheduler library. Click on avast! Emergency Update, then right click and choose Run. Wait a few minutes and reboot.
2.- Or you can go directly to C:, Program files, AVAST Software, Avast Business, and execute AvastEmUpdate.exe. Wait a few minutes and reboot.
It is possible that first reboot after that don't run correctly and that you have to force reboot with the reset button, but once rebooted all should be fine.
Good luck.