Avast ransomware detection stops LibreOffice from opening files

[Ferrari328]

Avast 20.7.2425 (build 20.7.5568.590) Windows 10

If I try to open any LibreOffice file in Documents, regardless of extension, I get "file locked by unknown user". If I open a file on a different partition or a different folder that is not listed as protected, it works fine. I can create a new file, save it but when trying to open it later, I get the same error. Disabling the Ransomware protection makes the problem go away. I get no notifications from Avast at all. Something also removed the LibreOffice application from my PC, so I had to reinstall it. I tried to add LibreOffice Base and Writer to allowed apps but it makes no difference.

[rocksteady]

I tried to add LibreOffice Base and Writer to allowed apps but it makes no difference.

That was the first thing to come to mind.
I had a similar problem with a Image application, but in my case was fixed by adding that to permitted programs.
I wonder why that solution is not working for LibreOffice.

Do you have free or Premium (paid) version of Avast?

[Ferrari328]

I have the free version.

[Michael529]

Avast 20.7.2425 (build 20.7.5568.590) Windows 10

If I try to open any LibreOffice file in Documents, regardless of extension, I get "file locked by unknown user". If I open a file on a different partition or a different folder that is not listed as protected, it works fine. I can create a new file, save it but when trying to open it later, I get the same error. Disabling the Ransomware protection makes the problem go away. I get no notifications from Avast at all. Something also removed the LibreOffice application from my PC, so I had to reinstall it. I tried to add LibreOffice Base and Writer to allowed apps but it makes no difference.

This happened on my system as well, just after I had installed LibreOffice 7.0.1. But, unlike your experience, I got an Avast pop-up warning from the Ransomware shield asking whether to allow soffice to access Documents. Answer "yes" and no more problems. LibreOffice is now shown as an allowed app in the Ransomware shield settings.
Have you tried going into the Ransomware settings and adding an allowed app manually? It is an option that doesn't really standout towards the bottom of the screen.

[Ferrari328]

I had notifications turned off, so I never saw anything. Turning notifications on, still no message. "I tried to add LibreOffice Base and Writer to allowed apps but it makes no difference."

[Ferrari328]

I turned on notifications in Avast. Uninstalled LibreOffice, rebooted. Installed LibreOffice again. Rebooted and now everything works with ransomware protection turned on.