Fix 'The User Profile Service Failed the Sign-in'

The "User Profile Service Failed the Sign-in" error is a common and frustrating issue encountered on Windows operating systems, particularly Windows 7,…

The "User Profile Service Failed the Sign-in" error is a common and frustrating issue encountered on Windows operating systems, particularly Windows 7, 8.1, 10, and 11. This error prevents a user from logging into their profile, often leaving them with a temporary profile or a completely inaccessible desktop. It typically arises when the User Profile Service (ProfSvc) fails to load a user's profile correctly, usually due to corruption in the registry entries associated with the profile or issues with the profile folder itself. This article details a robust, multi-step approach to resolving this problem, from registry manipulation to complete profile reconstruction.

Understanding the User Profile Service Error

When a user attempts to log in, Windows relies on the User Profile Service to load their personalized settings, documents, and environment. Each user profile has a unique Security Identifier (SID) stored in the Windows Registry, specifically under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList. For each SID, there's a corresponding profile path (e.g., C:\Users\username). The error occurs when this link is broken, the profile folder is inaccessible, or the registry entry becomes corrupt. A common symptom is the user being logged in with a "temporary profile," indicated by a message like "You have been logged on with a temporary profile."

The core of the problem often lies in duplicate or corrupted registry entries for a user's SID, sometimes with a .bak extension appearing on one of them, indicating a backup. The system might try to load the incorrect or broken entry, leading to the sign-in failure.

Initial Access and Diagnostics

To resolve this, you typically need administrative access to the affected system. Since the primary user cannot log in, the first step is to gain access via an alternative route:

Boot to Safe Mode: This is often the most reliable method. During startup, repeatedly press F8 (Windows 7/8) or navigate through Advanced Startup Options (Windows 10/11 - typically accessed by holding Shift while clicking Restart, then "Troubleshoot" > "Advanced options" > "Startup Settings" > "Restart" > select option 4 or 5 for Safe Mode).
Sign in with Another Administrator Account: If a local administrator account is available and working, use it. This provides full access to the system, including the Registry Editor.
Enable the Built-in Administrator (if no other admin exists): If no other admin account is accessible, you might need to enable the built-in administrator account. This can be done from the command prompt within the Advanced Startup Options (Shift + F10 during installation, or "Troubleshoot" > "Advanced options" > "Command Prompt").
```
net user administrator /active:yes
net user administrator NewPassword123!
```
After enabling, restart and log in as "Administrator" with the password you set. Remember to disable it afterward: net user administrator /active:no.

Method 1: Repairing Corrupted Registry Profile Entries

This method involves manipulating the registry entries for the problematic user profile. This is the most common fix.

Step 1: Access the Registry Editor

Once logged in with an administrator account (preferably in Safe Mode), open the Registry Editor:

Win + R

Type regedit and press Enter. Confirm the UAC prompt.

Step 2: Navigate to ProfileList

In the Registry Editor, navigate to the following path:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList

Step 3: Identify and Correct Corrupted SIDs

Under the ProfileList key, you will see several subkeys, each representing a user's SID. Look for SIDs that match the problematic user. You are looking for two entries for the same SID:

One without a .bak suffix (e.g., S-1-5-21-XXX)
One with a .bak suffix (e.g., S-1-5-21-XXX.bak)

The entry with .bak is usually the good, working profile entry that Windows failed to load correctly, while the one without .bak is often the corrupted entry causing the temporary profile.

Perform the following actions carefully:

Rename the corrupted SID: Select the SID entry without the .bak suffix. Right-click it, select "Rename", and append .old to its name (e.g., S-1-5-21-XXX.old). This effectively disables the bad entry.
Restore the good SID: Select the SID entry with the .bak suffix. Right-click it, select "Rename", and remove the .bak suffix (e.g., change S-1-5-21-XXX.bak to S-1-5-21-XXX).
Verify and Adjust Values (for the now-restored SID):
- Select the newly renamed (restored) SID entry.
- In the right pane, locate the State DWORD value. Double-click it and ensure its "Value data" is 0. If not, change it to 0.
- Locate the RefCount DWORD value. Double-click it and ensure its "Value data" is 0. If not, change it to 0.

Note on Missing .bak: If you only find one SID entry for the user and it does not have a .bak, it means the existing entry is the one causing the problem. In this case, rename it by adding .old, then proceed to Method 2 or 3. There's no .bak to restore.

Step 4: Reboot and Test

Close the Registry Editor and restart your computer normally. Attempt to log in with the previously problematic user account. If successful, the issue is resolved.

Method 2: Creating a New User Profile (Data Migration)

If Method 1 fails, or if the registry entries are too corrupted to salvage, creating a new user profile and migrating data is the next best approach. This ensures a clean profile but requires transferring user data manually.

Step 1: Create a New Administrator Account (if needed)

If you only have one admin account and it's the one that's broken, ensure you have another administrator account available to perform these steps. If not, create one from another admin account or by enabling the built-in administrator.

net user NewAdminAccount NewPassword /add
net localgroup administrators NewAdminAccount /add

Step 2: Create a New User Profile

Go to Settings (Win + I) > Accounts > Family & other users.
Click Add someone else to this PC.
Choose I don't have this person's sign-in information, then Add a user without a Microsoft account.
Enter a new username and password (e.g., New.Username). Make this account an administrator if desired, but a standard user is usually sufficient.

Step 3: Migrate Data from the Old Profile

This is the most critical step to avoid data loss.

Using the administrative account, navigate to C:\Users\.

Locate the old, broken user profile folder (e.g., C:\Users\Old.Username).
Locate the newly created user profile folder (e.g., C:\Users\New.Username).
Do NOT copy the following folders from the old profile:
- NTUSER.DAT, NTUSER.DAT.LOG1, NTUSER.DAT.LOG2 (these are hidden system files that define the profile's registry hive)
- AppData (contains application settings, often better to let apps rebuild these)
- Local Settings (a hidden folder, similar to AppData)
Copy the essential data folders:
- Documents
- Downloads
- Favorites
- Music
- Pictures
- Videos
- Desktop (for desktop icons and files)
- Any custom folders the user created directly under their profile (e.g., C:\Users\Old.Username\Projects)
Paste these folders into the corresponding locations within the new user profile (e.g., copy Old.Username\Documents to New.Username\Documents).

You may encounter permission issues. Right-click the old profile folder > Properties > Security tab > Advanced > Change owner to your current admin account. Then grant full control to your current admin account.

Step 4: Delete the Old Profile (Optional, After Verification)

Once you've successfully logged into the new profile and verified all necessary data has been migrated, you can optionally delete the old, broken profile to free up disk space and remove potential lingering issues.

Go to System Properties (Win + R, type sysdm.cpl, press Enter).
Navigate to the Advanced tab.
Under "User Profiles", click Settings....
Select the old, broken profile and click Delete Profile. Be absolutely sure you've backed up all necessary data before doing this, as it's irreversible.

Method 3: Advanced Profile Folder Check

In rare cases, the issue might be with the profile path itself or permissions on the physical profile folder.

Step 1: Verify ProfileImagePath

After navigating to HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList in regedit (as in Method 1), select the SID corresponding to the problematic user.

In the right pane, locate the ProfileImagePath string value. Double-check that this path correctly points to the user's profile folder (e.g., C:\Users\username). If it's incorrect, modify it to the correct path. A common mistake is a typo or an incorrect drive letter.

Step 2: Check Folder Permissions

Using an administrative account, navigate to C:\Users\ in File Explorer.

Right-click on the problematic user's profile folder (e.g., C:\Users\Broken.Username) and select Properties.
Go to the Security tab.
Click Edit... to change permissions.
Ensure that the user account itself (e.g., Broken.Username) has at least "Read & execute", "List folder contents", and "Read" permissions. Ideally, it should have "Full control".
Click Advanced. Ensure that the correct user account is listed as the Owner of the folder. If not, change the owner to the problematic user account. Propagate permissions if necessary.
It's also crucial that SYSTEM and Administrators groups have "Full control".

Incorrect permissions can prevent the User Profile Service from accessing the necessary files during login.

Common Pitfalls

Not backing up the registry: Before making any registry changes, always export the ProfileList key (or the entire registry) as a .reg file. This allows for quick restoration if something goes wrong.
Copying NTUSER.DAT: When creating a new profile and migrating data, never copy NTUSER.DAT or the AppData folder. These files contain profile-specific registry hives and application settings that can corrupt a new profile if transferred directly.
Forgetting to make a new admin account: If the only admin account is broken, you risk locking yourself out of the system if you don't have a backup admin or enable the built-in one.
Incomplete data migration: Thoroughly check the new profile for all critical user data before deleting the old one. Users often store files in non-standard locations.
Ignoring Safe Mode: Attempting registry fixes or profile migrations in normal boot mode can lead to files being in use or additional errors. Safe Mode provides a cleaner environment.