Fix User Profile Service Failed Logon on Windows

The “User Profile Service failed the logon” error appears when Windows cannot load your user profile during sign-in, often after a profile corruption or a failed update. The fix is to repair the profile through the Registry Editor or create a new local administrator account, and this guide walks through both methods step by step.

What Causes the User Profile Service Logon Failure

This error typically occurs when the user profile registry key is corrupted, the profile folder is damaged, or the profile service cannot read the correct ProfileImagePath value. Common triggers include:

• Interrupted Windows updates that leave profile data in an inconsistent state.
• Antivirus or disk cleanup tools that accidentally delete profile files.
• Manual edits to the registry that break the profile’s SID (Security Identifier) mapping.
• Disk errors or sudden power loss while Windows is writing profile data.

The error message usually appears right after you enter your password, and Windows logs you out immediately. In some cases, you may only see a black screen with the error text.

Before You Start: What You Need

To fix the issue you need administrator access to the computer. If you are locked out of your only admin account, you can still access the built-in Administrator account by booting into Safe Mode (Shift + Restart from the login screen) or using another admin account if one exists. You also need the exact name of the affected user profile and its SID, which you can find using the Registry Editor.

Method 1: Repair the Profile in the Registry

This method restores the link between your user account and its profile folder. It works when the profile folder still exists but Windows cannot find it.

1. Log on with an administrator account (or boot into Safe Mode and use the built-in Administrator).
2. Press Win + R, type regedit, and press Enter.
3. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList.
4. Look for a folder that starts with S-1-5-21- and ends with .bak (for example, S-1-5-21-1234567890-1234567890-1234567890-1001.bak). This is a backup of a corrupted profile.
5. If you see a folder with the same SID but without the .bak suffix, right-click the .bak folder and select Delete.
6. Rename the .bak folder by right-clicking it and selecting Rename, then remove the .bak part.
7. Click on the renamed folder, then double-click ProfileImagePath in the right pane. Make sure it points to the correct profile folder (e.g., C:\Users\YourName). If it is wrong, change it to the correct path.
8. Close the Registry Editor and restart your computer. Try logging in with the affected account.

If this does not work, the profile may be too damaged to repair. In that case, you can copy your files from the old profile folder to a new profile.

Method 2: Create a New User Profile and Migrate Files

If the registry repair fails, creating a fresh profile is the most reliable fix. This gives you a clean profile while preserving your personal files.

1. Log on with an administrator account.
2. Open Settings > Accounts > Family & other users (Windows 10/11).
3. Click Add account and choose Add a user without a Microsoft account (or create a local account). Follow the prompts to create a new user.
4. Log out and log in with the new account. This creates a fresh profile folder under C:\Users\NewName.
5. Copy your documents, pictures, desktop items, and other files from the old profile folder (C:\Users\OldName) to the new one. You may need to take ownership of the old folder first (right-click > Properties > Security > Advanced > Change owner).
6. Once everything is copied, you can either keep using the new account or delete the old one (after verifying all important data is transferred).

What to Do If You Cannot Log In at All

If you have no other admin account and the built-in Administrator is disabled, you can still access it via Safe Mode:

1. On the login screen, click the power icon, hold Shift, and click Restart.
2. Choose Troubleshoot > Advanced options > Startup Settings > Restart.
3. Press 4 or F4 to boot into Safe Mode.
4. In Safe Mode, the built-in Administrator account appears on the login screen (if it was ever enabled). If not, you can enable it from another admin account.

If you cannot boot into Safe Mode, you can use a Windows installation USB to access the Command Prompt and enable the Administrator account or back up files before reinstalling.

Common Mistakes and Misconceptions

One common mistake is deleting the profile folder directly from C:\Users without fixing the registry. This can cause the error to persist because the registry still points to a missing folder. Another misconception is that the error means your files are gone; in most cases, the files remain intact in the profile folder even if the profile cannot load.

Also, some users try to fix this by creating a new Microsoft account, but that does not solve the underlying profile corruption. The issue is tied to the local profile, not the account type.

Preventing Future Profile Corruption

To reduce the chance of this happening again:

• Always shut down Windows properly, not by holding the power button.
• Keep Windows updated, but avoid interrupting updates.
• Run chkdsk /f on your system drive periodically to check for disk errors.
• Use a reliable antivirus and avoid cleaning tools that modify profile folders.
• Back up your important files regularly, either to an external drive or cloud storage.

Frequently Asked Questions

Will I lose my files if I create a new profile?

No, your files remain in the old profile folder. You need to manually copy them to the new profile. The new profile starts empty, so you must migrate your documents, pictures, and other data.

Can I fix this without reinstalling Windows?

Yes, in most cases the registry repair or new profile method works without reinstalling. Reinstalling is a last resort if the system files are severely damaged.

Why does the error happen after a Windows update?

Windows updates can sometimes corrupt profile registry keys if the update is interrupted or if there is a conflict with third-party software. The profile service may then fail to load the profile.

Is the built-in Administrator account safe to use?

The built-in Administrator account has full system access, so it should only be used for troubleshooting. After fixing the issue, disable it again via net user administrator /active:no in Command Prompt (run as admin).

What if the registry repair shows no .bak folder?

If there is no .bak folder, the profile may be completely missing from the registry. In that case, try the new profile method, or use System Restore to revert to a point before the issue started.

Related

• iPhone App Not Working on iOS 12? Fixes That Work
• How to Unlock a Samsung Phone Without the Password
• How to Install Custom Recovery on Samsung Galaxy Grand Neo