Windows & BSOD · critical

How to fix CRITICAL_PROCESS_DIED0x000000EF

Windows & BSOD troubleshooting guide

What this error means

Windows stopped because a system process it cannot run without ended unexpectedly. These processes manage things like sign-in, sessions and system services, so Windows treats their loss as fatal and restarts. The usual causes are damaged system files after a failed update or an interrupted shutdown, a driver or security program interfering with system processes, or a storage drive that returns bad data. It can appear once, or in a loop that stops Windows from starting.

Updated

Applies to
Windows 11 and Windows 10
Difficulty
Intermediate
Before changes
Recovery tools change system files; a reset removes installed apps

Reviewed by Matyáš Rada · Documentation checked: 2026-10-30 · Checked against Microsoft's bug check and stop code troubleshooting documentation; not tested on every configuration.

Before you begin

If Windows still starts, back up important files now. If it does not, the recovery environment in step 1 lets you work without losing data; avoid Reset this PC until step 7. If Windows cannot start, see the startup guide.

Work through these checks

0 of 7 complete
01Get into Windows or the recovery environment

Most fixes need either a working desktop or the Windows Recovery Environment (WinRE).

  1. If Windows starts, continue with step 2.
  2. If the PC crashes during startup, switch it on and hold the power button as soon as the Windows logo appears to force it off. After the third interrupted start, Windows opens Automatic Repair. Choose Advanced options.
  3. In Troubleshoot > Advanced options, first try Startup Repair.
  4. If that does not help, open Startup Settings > Restart and press 4 or 5 for Safe Mode.
What to expect

You reach the desktop, Safe Mode or the recovery menu.

If it does not help

If even Safe Mode crashes, use the recovery menu options in steps 2 and 3.

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02Undo the most recent change

This stop code often starts right after an update, a new driver or new security software.

  1. If you installed antivirus, VPN, system cleaner or tuning software recently, uninstall it in Safe Mode (Settings > Apps > Installed apps).
  2. If it started after a Windows update, use Troubleshoot > Advanced options > Uninstall Updates in the recovery menu, starting with the latest quality update.
  3. Alternatively, use System Restore (recovery menu, or search "Create a restore point" > System Restore) and pick a point from before the problem.

System Restore removes apps and drivers installed after the restore point, but not your personal files.

What to expect

Windows starts and runs normally again.

If it does not help

If you removed an update, pause updates for a week and install it again later; a fixed version is often released.

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03Repair Windows system files

Damaged system files are the most common cause, and Windows can repair them from its own component store.

  1. In Windows or Safe Mode, right-click Start and open Terminal (Admin).
  2. Run DISM /Online /Cleanup-Image /RestoreHealth and wait for it to finish.
  3. Run sfc /scannow, then restart.
  4. If Windows does not start at all, open Command Prompt from the recovery menu and run sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows (the drive letter may be different in recovery; check it with dir C:\ first).
What to expect

SFC reports that it found no integrity violations, or that it repaired them.

If it does not help

If SFC reports files it could not repair, run DISM and SFC once more after a restart, then go to step 6.

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04Check the system drive

If the drive returns damaged data, system processes crash when they load it.

  1. In Terminal (Admin), run chkdsk C: /scan. If it reports problems, run chkdsk C: /f and allow it to run at the next restart.
  2. Check the drive's health in its maker's tool or CrystalDiskInfo.
What to expect

No file system errors and good drive health.

If it does not help

If the drive reports bad health or growing errors, back up immediately and replace it before reinstalling Windows.

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05Scan for malware and test the memory

Malware that hooks into system processes, and faulty RAM, can both kill critical processes.

  1. Open Windows Security > Virus & threat protection > Scan options > Microsoft Defender Antivirus (offline scan) > Scan now.
  2. Run Windows Memory Diagnostic (Win + R, mdsched.exe) and choose Restart now and check for problems.
What to expect

No threats are found and the memory test passes.

If it does not help

If the memory test reports errors, follow the memory test errors guide on this site.

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06Reinstall Windows while keeping your files

A repair installation replaces all Windows system files but keeps your apps and documents.

  1. On Windows 11, open Settings > System > Recovery and, if offered, choose Fix problems using Windows Update > Reinstall now.
  2. Otherwise, download the Windows installation media from Microsoft, run setup.exe from within Windows, and choose to keep personal files and apps.

Make sure your backup is current before starting.

What to expect

Windows is reinstalled over itself and the crashes stop.

If it does not help

If the repair install cannot run because Windows does not start, continue with step 7.

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07Back up and reset if nothing else works

When system files cannot be repaired, a reset gives a clean Windows installation.

  1. Back up your files, if necessary by connecting the drive to another PC.
  2. Choose Reset this PC (in Settings > System > Recovery, or Troubleshoot in the recovery menu) and pick Keep my files.
  3. If the crash returns on a clean installation, the cause is hardware: the drive or memory. Contact the PC manufacturer.

Reset this PC removes installed apps even when you choose Keep my files.

What to expect

A clean Windows installation that runs without the stop code.

If it does not help

Reinstall your apps one at a time, so you notice if a particular program brings the crash back.

Browse related errors

Possible causes

  • Damaged Windows system files (failed update, power loss, forced shutdown)
  • A recent update, driver or security program interfering with system processes
  • Errors or failing sectors on the system drive
  • Malware tampering with system processes
  • Faulty RAM corrupting data

Useful Windows tools

These commands open Windows tools. Review changes before applying them.

eventvwr.msc
mdsched.exe
msinfo32

Sources & further reading