This is not for general usage, but an „admin-Jumphost“-computer/vm which needs to get flash enabled from time to time and is never used for public internet browsing… There it might be an un-dogmatic solution to install the last Firefox 78.15 ESR Release. Find it here: https://ftp.mozilla.org/pub/firefox/releases/78.15.0esr/win64/de/ Disable Auto-Update That’s easy Firefox Settings => Update Settings => „Disable Automatic Updates“ Disable Update-Notification That’s harder – Firefox guys (think to) know better what’s good for their users and they don’t even provide an „about:config“-switch: fail! Add the following registry Key: Add the following 32-Bit DWORD with value set to and restart Firefox.Read More →