Are you saying that you updated Opera browser using Avast Software Updater and this was the result?
Do you have Avast Online Security Extension in Opera Browser?
Have you tried "Recovery" in Opera Menu> Update & Recovery Settings?
Have you tried a full system "Restart" (not Shutdown/Startup cycle) to see if improves things?
So we can help you, tell us your Windows operating system and version, Version of Avast (free/paid) and version of Opera.
Also do you have any other antivirius/anti-malware programs installed.
If you want to turn off Avast shields, easiest way is right click the Avast icon in system tray
then click Shields Control.