how to fix “The User Profile Service failed the logon” error message

Source: You receive a “The User Profile Service failed the logon” error message

1. try restarting your computer and logging on with your user account again to resolve the issue.
2. If you restart your computer and it does not resolve this issue, use the following methods to resolve this issue.
3. Click Start, type regedit in the Search box, and then press ENTER.
4. In Registry Editor, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
5. In the navigation pane, locate the folder that begins with S-1-5 (SID key) followed by a long number.
6. Click each S-1-5 folder, locate the ProfileImagePath entry in the details pane, and then double-click to make sure that this is the user account profile that has the error.
7. If you have two folders starting with S-1-5 followed by some long numbers and one of them ended with .bak, you have to rename the .bak folder. To do this, follow these steps:
   1. Right-click the folder without .bak, and then click Rename. Type .ba, and then press ENTER.
   2. Right-click the folder that is named .bak, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
   3. Right-click the folder that is named .ba, and then click Rename. Change the .ba to .bak at the end of the folder name, and then press ENTER.
8. If you have only one folder starting with S-1-5 that is followed by long numbers and ends with .bak. Right-click the folder, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
9. Click the folder without .bak in the details pane, double-click RefCount, type 0, and then click OK.
10. Click the folder without .bak, in the details pane, double-click State, type 0, and then click OK.
11. Close Registry Editor.
12. Restart the computer.
13. Log on again with your account.

How to back up and restore the registry in Windows

Back up the registry

Windows 8.1 and Windows 8

1. Swipe in from the right edge of the screen, and then tap Search. Or, point to the upper-right corner of the screen, and then click Search.
2. In the search box, type regedit.exe, and then press Enter. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
3. In Registry Editor, locate and click the registry key or subkey that you want to back up.
4. Click File > Export.
5. In the Export Registry File dialog box, select the location where you want to save the backup copy to, and then type a name for the backup file in the File name field.
6. Click Save.

Windows 7 and Windows Vista

1. Click Start, type regedit.exe in the search box, and then press Enter. If you’re prompted for an administrator password or confirmation, type the password or provide confirmation.
2. In Registry Editor, locate and click the registry key or subkey that you want to back up.
3. Click File > Export.
4. In the Export Registry File dialog box, select the location where you want to save the backup copy to, and then type a name for the backup file in the File name field.
5. Click Save.

Restore the registry

Windows 8.1 and Windows 8

1. Swipe in from the right edge of the screen, and then tap Search. Or, point to the upper-right corner of the screen, and then click Search.
2. In the search box, type regedit.exe, and then press Enter. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
3. In Registry Editor, click File > Import.
4. In the Import Registry File dialog box, select the location where you saved the backup copy to, click to select the backup file, and then click Open.

Windows 7 and Windows Vista

1. Click Start, type regedit.exe in the search box, and then press Enter. If you’re prompted for an administrator password or confirmation, type the password or provide confirmation.
2. In Registry Editor, click File > Import.
3. In the Import Registry File box, select the location where you saved the backup copy to, click to select the backup file, and then click Open.

How to back up and restore the registry in Windows.