User Profile Service failed the sign-in 🪟 Windows

The User Profile Service failed the sign-in. User profile cannot be loaded.

Windows can’t load your profile — the profile registry entry or NTUSER.DAT is corrupt, or the Default profile is damaged.

Seen on: Windows

Meaning

Interrupted updates, disk errors, or profile folder renames leave a .bak profile key in ProfileList or a damaged NTUSER.DAT. New accounts fail if C:\Users\Default is broken.

Common causes

  • Corrupt NTUSER.DAT
  • ProfileList key duplicated with .bak
  • Damaged Default profile (new users)
  • Disk errors

⚡ Quick fix

  1. Sign in with another admin account (or Safe Mode)
  2. Fix the ProfileList key (.bak swap)
  3. Create a new profile and copy data

Detailed fix by platform

Windows

  1. reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList" /s /f .bak

How to diagnose

  1. Registry — .bak keys in ProfileList
  2. Scope — One user or new users?
  3. Disk — chkdsk

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

🧠 Still stuck? Analyze your error

Paste the full message, response headers or stack trace — we'll detect the platform and point to the most likely cause.