Resolving User Profile service failed logon

This article is about resolving the error message:"The User Profile Service failed the logon" on Windows Vista or Windows 7 when caused by an anti-virus tool running at startup.

The scenario

You boot your PC but instead of being able to logon you are greeted with the unhelpful message:

"The User Profile Service failed logon"

This can be caused by a variety of reasons but this article deals with users of Windows Vista or Windows 7 that are using an anti-virus tool.

How the problem occurs

Your computer boots and a component of your anti-virus software is scanning your PC at the same time that you are attempting to log on. Windows attempts to resolve an issue and the result is that part of your registry is now incorrect and will need repairing in order for you to be able to log on to your PC again.

How to resolve the problem

To resolve the problem we need to dip into the registry and restore a backup entry verifying settings are correct.

The following instructions will guide you through the process:

  1. Reboot your PC and tap the F8 key until you get a boot menu
  2. Select the option to boot into Safe Mode
  3. When your PC has booted into Safe Mode click START and type 'regedit' into the Search box and hit enter
  4. In the Registry Editor navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
  5. There will be two folders with long names starting with 'S-1-5' and one will end with '.bak'. This is the backup copy that we need to restore
  6. Right-click on the folder ending '.bak' and rename it to '.fxd'
  7. Right-click on the other folder that did not end in '.bak' and add '.bak' to the end of its name
  8. Right-click on the folder that we renamed with '.fxd' at the end and delete the '.fxd' from the end of the file name (we have now swapped their folder names around)
  9. Open the folder without the '.bak' and double-click 'RefCount' and check that Base is Hexadecimal and Value data is set to 0 (zero). If not, correct then click OK.
  10. Next double-click 'State' and check that Base is Hexadecimal and Value data is 0 (zero). If not, correct then click OK.
  11. Close the Registry Editor
  12. Restart your computer and logon as normal


If this problem occurs again check that you have the latest version of your anti-virus software by visiting the software vendors web site rather than using the check for updates option. A new version of the engine may be available that addresses this problem. Alternatively consider using a different anti-virus tool.

If you have any feedback regarding this article, or you have a suggestion for a new article, or just want to say thanks for the info then feel free to drop me an email at

Article date: 27th March 2014

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