Hi, this is not a Firefox Support Issue : Please see Microsoft for any updates and downloads for Microsoft .NET Framework Assistant *https://docs.microsoft.com/en-us/dotnet/framework/wpf/app-development/firefox-add-ons-to-support-net-application-deployment No idea what year above is from, some have been disabled by Firefox so you may want to check in a Win7 forum : *https://www.sevenforums.com/ *https://www.bleepingcomputer.com/forums/f/167/windows-7/ Please let us know if this solved your issue or if need further assistance.