Fix Windows 10/11 “User Profile Service Failed the Sign-In”: Safe Mode, Registry, and New Profile

The fastest safe fix for “The User Profile Service failed the sign-in. User profile cannot be loaded” is to sign in through Safe Mode or another administrator account, back up the affected profile, then either repair the matching profile registry entry or create a clean replacement profile and move only your personal files. This guide applies to Windows 10 and Windows 11 on personal PCs. Do not delete the old account or its folder until the replacement account has been tested and all needed files have been copied.

Prerequisites and compatibility​

You need one of the following:

• The password for the affected local or Microsoft account. PIN and Windows Hello sign-in are unavailable in Safe Mode, so use the account password.
• Another administrator account already present on the PC, or the ability to sign in to Safe Mode with the affected account.
• An external drive or enough free storage to copy important files before changing the registry.
• The BitLocker recovery key if Windows asks for it when entering the Windows Recovery Environment.

This procedure is for a local Windows profile stored under C:\Users\<username>. If the PC is managed by a business, school, domain, or Microsoft Entra ID organization, contact its administrator before changing registry profile mappings or creating replacement accounts.

Primary procedure​

1. Try one normal restart first​

A failed profile load can be temporary, especially after an interrupted update or improper shutdown.

1. At the sign-in screen, select Power in the lower-right corner.
2. Select Restart — do not choose Shut down.
3. Try signing in again.

If Windows signs you in but displays a blank desktop and a message such as “We can’t sign in to your account,” you may be using a temporary profile. Do not save files to that temporary desktop. Continue with the backup and repair steps below.

2. Start Safe Mode with Networking​

Safe Mode starts Windows with a limited set of drivers and services. If the account works there, the issue may involve the profile mapping, a startup component, or a damaged profile rather than basic authentication.

1. On the sign-in screen, hold down Shift.
2. While holding Shift, select Power > Restart.
3. Release Shift when the blue Choose an option screen appears.
4. Select Troubleshoot > Advanced options > Startup Settings > Restart.
5. After the restart, press 5 or F5 for Safe Mode with Networking.
6. Sign in using the account password, not its PIN.

Expected result: Windows starts with a lower-resolution desktop and “Safe Mode” text near the screen corners.
If the affected account still cannot sign in, look for another account on the lower-left side of the sign-in screen. Select it, or choose Other user and enter credentials for another local administrator.

3. Back up the old profile before changing anything​

If you can sign in with the affected account in Safe Mode, another administrator account, or a temporary profile with administrative rights, back up the old profile’s personal data first.

1. Connect an external drive if available.
2. Open File Explorer.
3. Browse to:
   C:\Users
4. Open the folder for the failed account. Its folder may have the original account name, a shortened name, or a suffix such as .000.
5. Copy these folders to the external drive or a safe folder outside C:\Users:
   
   Code:

   Desktop
   Documents
   Downloads
   Pictures
   Music
   Videos
   Favorites

6. Also check for application-specific files in:
   • C:\Users\<old-user>\OneDrive
   • C:\Users\<old-user>\Documents
   • C:\Users\<old-user>\AppData\Roaming
   • C:\Users\<old-user>\AppData\Local

Warning: Do not copy the entire profile folder into a new profile. In particular, do not copy NTUSER.DAT, NTUSER.DAT.LOG*, ntuser.ini, or the whole AppData tree wholesale. Those files contain registry settings, cached application state, and potentially the corruption that caused the sign-in failure.
If File Explorer says you do not have permission to open the old folder, select Continue when prompted for administrator permission. If access is denied even as an administrator, stop before changing ownership indiscriminately; copy data through an approved backup method or use the alternate recovery path later in this guide.

4. Identify the affected profile’s registry entry​

Windows maps every user account’s security identifier (SID) to a profile folder through the ProfileList registry location. A duplicate SID with a .bak extension is a common, repairable profile-mapping issue.

1. Press Windows + R.
2. Type:
   regedit
3. Select OK and approve the User Account Control prompt.
4. Browse to:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
5. Expand ProfileList. You will see folders with names beginning with S-1-5-....
6. Select each long S-1-5-21-... SID key and check the ProfileImagePath value in the right pane.
7. Find the entry whose ProfileImagePath points to the old profile folder, for example:
   C:\Users\Alex

Ignore standard built-in profile entries such as S-1-5-18, S-1-5-19, and S-1-5-20.

5. Export the profile registry key as a rollback copy​

Warning: The next steps change the registry. Renaming or editing the wrong SID can prevent another account from loading. Do not delete any SID key unless you have confirmed its ProfileImagePath and exported a backup.

1. In Registry Editor, right-click the relevant SID key or keys.
2. Select Export.
3. Save the .reg file somewhere outside the affected profile, such as an external drive or C:\Temp.
4. Give it a clear name, such as:
   ProfileList-backup-Alex.reg

Rollback: If a registry change makes the situation worse, sign in using another administrator or Safe Mode, double-click the exported .reg file, approve the import, and restart.

6. Repair a duplicate .bak SID mapping, if present​

Perform this step only if you find two nearly identical SID keys for the same account: one normal key and one ending in .bak.
Example:
Check both keys’ ProfileImagePath values. Usually, the .bak key points to the real old profile folder.

1. Right-click the SID without .bak and select Rename.
2. Add .old to its name. For example:
   S-1-5-21-...-1001
   becomes:
   S-1-5-21-...-1001.old
3. Right-click the SID ending in .bak and select Rename.
4. Remove only the .bak suffix so that it becomes the normal SID name.
5. Select the newly renamed normal SID key.
6. In the right pane, double-click State. Set Value data to:
   0
   Select OK.
7. If a RefCount value exists, double-click it and set Value data to:
   0
   Select OK.
8. Confirm that ProfileImagePath points to the correct existing folder, such as:
   C:\Users\Alex
9. Close Registry Editor.
10. Restart the PC normally and attempt to sign in to the repaired account.

Expected result: Windows loads the usual desktop, files, and settings rather than showing the User Profile Service error or a temporary profile.
If there is only one SID ending in .bak and it clearly points to the correct old profile folder, export it first, rename it to remove .bak, set State and any existing RefCount to 0, then restart. Do not invent or delete duplicate keys merely because a .bak key exists.

7. Create a new administrator profile if repair fails​

If the error persists after the registry repair, or there is no clear .bak mapping, a new profile is the safer long-term solution.
Windows 11

1. Sign in using a working administrator account.
2. Open Settings > Accounts > Other users.
3. Under Add other user, select Add account.
4. Select I don’t have this person’s sign-in information.
5. Select Add a user without a Microsoft account.
6. Create a temporary local account with a strong password.
7. Back under Other users, select the new account.
8. Select Change account type.
9. Choose Administrator, then select OK.

Windows 10

1. Sign in using a working administrator account.
2. Open Settings > Accounts > Family & other users.
3. Under Other users, select Add someone else to this PC.
4. Select I don’t have this person’s sign-in information.
5. Select Add a user without a Microsoft account.
6. Create a new local account with a strong password.
7. Select the newly created account under Other users.
8. Select Change account type.
9. Choose Administrator, then select OK.
10. Sign out of the current account.
11. Sign in to the new account once. Windows creates C:\Users\<new-user> during this first sign-in.
12. Restart normally, then sign in to the new account again.

8. Move personal files into the new profile​

1. In the new account, open File Explorer and browse to:
   C:\Users\<old-user>
2. Copy your files from the old profile into the corresponding folders in:
   C:\Users\<new-user>
3. Start with Documents, Pictures, Videos, Music, Downloads, and Desktop.
4. Reinstall desktop applications as needed. Programs installed for all users may still work; applications configured only in the old profile may need to be reinstalled or signed in again.
5. Sign in to browsers, OneDrive, and other cloud-sync services using the new profile. Let cloud files finish syncing before deleting any local copies.

If you use a Microsoft account, you can switch the new local account to that Microsoft account after the new profile is stable. In Settings > Accounts > Your info, select the option to sign in with a Microsoft account instead, then complete the prompts.

Verification of success​

The repair or replacement profile is successful when all of the following are true:

1. You can restart Windows normally and sign in without Safe Mode.
2. The User Profile Service error no longer appears.
3. The desktop is not blank or temporary.
4. Your account folder under C:\Users matches the profile you are using.
5. Documents, Desktop, Downloads, and Pictures open correctly.
6. You can create a test file in Documents, restart the PC, and confirm the file remains available.
7. Windows Update opens normally from:
   • Windows 11: Settings > Windows Update
   • Windows 10: Settings > Update & Security > Windows Update

Keep the old profile folder and the exported registry backup until you have completed several normal restarts and verified that all personal files, browser data, cloud files, and application data have been recovered.

Troubleshooting and rollback/escalation​

Safe Mode rejects the PIN​

This is expected. Safe Mode does not support PIN or biometric sign-in. Select Sign-in options if needed, then enter the full password for the local account or Microsoft account.
If you recently changed a Microsoft account password online, connect the PC to the internet from the sign-in screen or use Ethernet, then use the current password. An offline PC may require the last password successfully used on that device.

No second administrator account is available​

Do not delete profile registry entries while locked out of every administrator account. First try Safe Mode and sign in with the affected account’s password. If that works, create the new administrator account immediately before attempting registry changes.
If no account can sign in, use Windows Recovery Environment options such as System Restore if a restore point exists. From the sign-in screen, hold Shift while selecting Power > Restart, then choose Troubleshoot > Advanced options > System Restore. Choose a restore point from before the sign-in failure.

The .bak repair does not work​

Restore the exported registry key if needed, then use the new-profile method. A .bak rename can correct a profile mapping problem, but it cannot repair every damaged user hive, permission problem, disk problem, or failed application configuration.
Do not keep changing State, RefCount, or ProfileImagePath values on guessed SID keys. Verify the profile path each time.

Windows signs in with a temporary profile​

Do not copy files into the temporary profile. Restart once, then inspect ProfileList from a working administrator account. Confirm whether the original SID points to the correct C:\Users\<old-user> folder and whether a duplicate .bak key exists. If the temporary profile repeats after a correct registry mapping, create a new profile and migrate data.

The old profile folder is missing or files cannot be copied​

Check whether OneDrive, File History, an external backup, or another cloud provider contains the missing folders. If the drive reports errors, freezes, disappears, or makes unusual noises, minimize further writes to it. Back up readable files first and investigate drive health before attempting extensive repairs.

The problem began after an update or crash​

After restoring access, open an elevated Command Prompt or Windows Terminal and run:
sfc /scannow
When it finishes, run:
DISM /Online /Cleanup-Image /RestoreHealth
Restart the PC after both commands complete. If either command reports unrepaired corruption, or profile failures return after successful repair, preserve the backup and use the new profile rather than continuing registry edits.

When to escalate​

Escalate to a repair technician, organizational IT administrator, or Microsoft support if multiple user accounts fail, every newly created account also receives a temporary profile, BitLocker recovery cannot be completed, the storage drive reports errors, or the old profile contains business-critical data that cannot be copied safely.