"You may not have the necessary permissions" when installing Firefox

Problem

When installing Firefox you get a dialog box stating:

“You may not have the necessary permissions to use all the features of the program you are about to run. You may run this program as a different user or continue to run the program as the current user.”

You are given the option to run as the current user or to run as a different user.

Cause

This can be caused if UAC is disabled on Vista or by faulty UAC settings in Windows 7.

Solution

Right click on the Firefox install file and click Run as administrator.
(Thanks to suggestions in the comments.)

If that does not work then select the correct tab below for further instructions:

Windows 7

  1. Click the Start button.
  2. In the Start Search box, type UAC.
  3. Click on ‘Change User Account Control Settings’.
  4. If it is currently set to Default, try setting it to Never Notify (drag the slider to the bottom) and click OK.
  5. If it is currently set to Never Notify, try setting it to Default.
  6. You can also try setting it to Never Notify, clicking OK then going back into it and changing it back to Default.
  7. Once done, try installing Firefox again.

Windows Vista

  1. Click the Start button.
  2. Click Control Panel.
  3. In the top right search box type UAC.
  4. ‘Turn User Account Control (UAC) on or off’ will appear. Click on it.
  5. If the checkbox is unchecked then check it and click OK.
  6. It will ask you to Restart. Click Restart Now.
  7. Try installing Firefox again.

76 comments

  2. Using Vista, I was not able to check my UAC box, but right clicking and running as administrator did the trick.

    Reply

  3. I was unable to check my UAC box too, but yes, thank you very very much for the “click with right button on the downloaded firefox and “run as administrator”.” – trick!

    Reply

  15. I was able to re-install Firefox by running as administrator, but now I can’t even open Firefox. At all.

    Reply

  32. Win 7: once you have changed your user account settings to “never notify” you also need to reboot for the settings to take effect.

    Reply

  54. THANK YOU I LOVE YOU!!!! THANKS FOR SAVING ME BEFORE I FUCKING SMASHED MY ASUS DESKTOP!!! THANK YOU!!!

    Reply

  65. I right clicked on file and clicked “run as administrator” and it worked for me.
    Thanks for help

    Reply

  70. Right click, run as admin works!! WHY THE HELL DO THEY MAKE IT LIKE THIS!!!!
    I just wasted 30 minutes on the bullshit!! And guys at Mozilla didn’t even know.

    But thanks again!

    Reply

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