Drag and Drop errors with Firefox Launcher Process enabled and Windows UAC disabled - How to Fix

Revision Information
  • Revision id: 184470
  • Created:
  • Creator: Aaron Klotz
  • Comment: The current article makes little sense as it is instructing users how to turn UAC off, when in fact we want them to turn UAC back on.
  • Reviewed: Yes
  • Reviewed:
  • Reviewed by: Noah_SUMO
  • Is approved? Yes
  • Is current revision? No
  • Ready for localization: Yes
  • Readied for localization:
  • Readied for localization by: Noah_SUMO
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Note: Applicable to all Windows builds, Firefox 67+

When running Windows as an Administrator with UAC disabled and the Launcher Process enabled, users running Firefox may experience unexpected behavior.

When the launcher process detects that it is running at a high integrity level, it will force Firefox to run at a medium integrity level. This intentional security feature is intended to prevent malicious code from gaining write access to sensitive areas of the OS. Windows does not allow programs running at a lower integrity level to send data to programs running at a higher integrity level. As a result, users may experience errors when trying to drag and drop a file from Firefox to another application.

How to Verify the Problem

To verify this condition, make sure the user is operating Windows as a full Administrator and has disabled User Account Control (UAC) settings. Enter about:support in the address bar and look under Application Basics for the Launcher Process entry. If enabled, you may experience errors when trying to drag and drop a file from Firefox to another application.

How to Fix

To fix the problem, users have two options.

Re-enable UAC

First, users can re-enable UAC on their PC. To do so, type UAC in the search field on your taskbar by right-clicking the Start button and selecting Search. Click Change User Account Control settings. To turn UAC on, drag the slider to Notify me only when apps try to make changes to my computer (default) and click OK. This option is the most secure fix available.

Start Firefox Using the No Deelevate Command

Alternatively, users can solve the issue by launching Firefox using the -no-deelevate command line option either directly from the command line or by editing their Firefox shortcut to do so.