Okay, the problem we experience is almost exactly like the one that's described here: https://support.mozilla.org/en-US/questions/1264949 , but in our case this happens on a Remote Desktop environment and we know why it happens. So we have this Remote Desktop Environment for a client of ours. When a user signs in to their online workplace, he or she will be signed on to one of the RD servers. Their profiles are stored on a user profile disk (UPD), which connects to their session upon logon. (I think the same issue will happen when roaming profiles or folder redirection is used.) We use Ninite Pro to install 3rd party updates on all of our servers. Ninite will only update Firefox when it's not in use so I think this is the reason why the Firefox versions become out of sync between the servers. When a user uses Firefox on server 1, which has version 69.0.2 installed and gets signed on to the other server the next time they log on, where version 69.0.1 is installed, they receive the warning: "You've launched an older version of Firefox". The only option there is to exit or create a new profile. Since they use certificates for their medcial administration software, this is a huge inconvenience. Using firefox.exe -allow-downgrade solves the problem for now, but I understand that's not the best solution. I will disable the Ninite updates for now and update Firefox to the latest version when everybody signed off. I've also explained the situation to Ninite support and suggested an option to 'bind' servers to update when all servers are ready to update. I would like suggest Mozilla to loosen the version check a little. I mean, there can't be a huge difference between 0.0.1 right? Thanks for reading!