Hi, that happens when a Policy has been added, which in your case is DisableAppUpdate. Is your PC in an enterprise environment (a company) and not your own personal one? You can find it by going to C: Drive > Program Files > Mozilla Firefox, then look for a folder named distribution, which will contain the Policy file. Deleting the file or the distribution folder then restarting Firefox should remove it, but if it's in a company's PC, you should probably talk to your IT department first. If it's your own personal PC something/someone must have added the file and folder which seems very strange. The GitHub link - this one I assume: https://github.com/mozilla/policy-templates/blob/master/README.md# and M.Kaply are genuine.

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Thanks for your reply. Checked the "C: Drive/PF/Mozilla FF but there is no folder called 'distribution' in there. What's next? And for your info this is not a company computer but a private one and no one can touch it. And FF was normally from the Mozilla servers downloaded. So someone (have no clue at all) added it. After discovering it, I already uninstalled the software and downloaded a new version and installed that one but the DisableAppUpdate was still there. Hope someone can help me out. I am standard very careful with strange situations and have a tightly secured computer wich I service regularly. Hope someone can help me with removing it.

If there's no distribution folder, you have to check in the registry under HKLM or HKCU -> \Software\Policies\Mozilla\Firefox

Yes as TyDraniu said, you will need to check the Registry: Open regedit by entering it into your PCs search box. Next, navigate through HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ then select and right click > Delete, any policy that is there, and if necessary you can also delete \Mozilla and \Firefox. You might need to restart Firefox and possibly your PC afterwards. Note: if you aren't confident with editing the Registry, I suggest you create a Windows Restore Point first, so can roll back if you make a mistake.

Something has created that policy on your PC - it's intended to prevent all Firefox updates, so if the policy comes back in the Registry after you have deleted it, then most likely a program that you installed on your PC when this started is causing it. If you didn't install anything yourself, then it could be caused by malware, so you can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller (for more info, see this alternate TDSSKiller download page)
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Further information can be found in the Troubleshoot Firefox issues caused by malware article.