Not sure of how they're connected, but Proton Pass seems to be causing this "Permission denied to access property "matches"" error. If I disable Proton Pass, everything works fine. Willing to provide logs or anything that might help. EDIT: Response from Proton > We are aware of this issue with the latest Firefox extension, and our team is working on a fix for it in a future version of the extension. In the meantime, they have rolled back the update, and to resolve the issue, simply re-install the extension, and the older stable version will be installed.