System file and kernel errors

CRITICAL_PROCESS_DIED (0x000000EF)

Stop code 0x000000EF, also written 0xEF. Here is what it means, what usually causes it, and the safest order to work through fixes on Windows 11 and Windows 10.

In short

A process Windows cannot run without stopped or was damaged, so Windows halted to protect itself.

What CRITICAL_PROCESS_DIED means

Windows keeps a small set of critical processes alive for as long as it runs. If one of them exits, or the data it depends on is damaged, Windows has no safe way to continue and stops with this code. The process is rarely the real culprit: the cause is usually whatever damaged it, such as a faulty driver, corrupted system files, unreliable storage or bad memory.

Common causes

A recently installed or updated driver, especially a storage, graphics or security-software driver
Corrupted Windows system files after an interrupted update or an unclean shutdown
A drive that is failing or returning read errors
Faulty or unstable RAM, including unstable XMP or EXPO profiles

How to fix CRITICAL_PROCESS_DIED

Work through these in order and test after each one. Stopping as soon as the crashes stop tells you which change mattered.

Undo the most recent change. If the blue screens began after a Windows update, a new driver or new software, remove that change first. Uninstall the update from Settings, Windows Update, Update history, or roll a driver back in Device Manager (right-click the device, Properties, Driver, Roll Back Driver).
Repair Windows system files. Open Terminal (Admin) and run sfc /scannow. If it reports damage it could not repair, run DISM /Online /Cleanup-Image /RestoreHealth, restart, and run sfc /scannow once more.
Check the health of the drive. Read the SMART data with the drive maker's tool or CrystalDiskInfo and look for reallocated or pending sectors, media errors and a low remaining-life figure. Back up important files first if the drive reports any warning.
Test the memory. Run Windows Memory Diagnostic (search for it in Start) for a quick check, then MemTest86 for several passes if the crashes continue. Any error points to a faulty stick or slot, or to memory settings the hardware cannot run reliably.
Start in Safe Mode if Windows will not load. Hold Shift while choosing Restart, or let Windows fail to start three times to open the recovery menu. Choose Troubleshoot, Advanced options, Startup Settings, Restart, then Safe Mode. If Windows is stable there, a driver or startup program is the likely cause.

When to stop and protect your data

If the code keeps returning on a freshly reinstalled Windows, suspect hardware, most often the drive or the memory. Back up your files before any reset or repair install.

Not sure this is your code?

The stop code appears as text on the blue screen. If the PC restarted before you could read it, open Event Viewer, then Windows Logs, then System, and look for a BugCheck event with ID 1001. You can also search all stop codes.

Related guides

Other system file and kernel errors

KERNEL_SECURITY_CHECK_FAILURE (0x139)

Frequently asked questions

What does CRITICAL_PROCESS_DIED mean?

A process Windows cannot run without stopped or was damaged, so Windows halted to protect itself. Windows keeps a small set of critical processes alive for as long as it runs. If one of them exits, or the data it depends on is damaged, Windows has no safe way to continue and stops with this code. The process is rarely the real culprit: the cause is usually whatever damaged it, such as a faulty driver, corrupted system files, unreliable storage or bad memory.

What usually causes CRITICAL_PROCESS_DIED?

Typical causes: A recently installed or updated driver, especially a storage, graphics or security-software driver; Corrupted Windows system files after an interrupted update or an unclean shutdown; A drive that is failing or returning read errors; Faulty or unstable RAM, including unstable XMP or EXPO profiles.

How do I fix CRITICAL_PROCESS_DIED (0x000000EF)?

A sensible order is: 1) Undo the most recent change; 2) Repair Windows system files; 3) Check the health of the drive; 4) Test the memory. If the code keeps returning on a freshly reinstalled Windows, suspect hardware, most often the drive or the memory. Back up your files before any reset or repair install.

Use this guidance carefully

A stop code can have several causes, and these steps are general guidance rather than a diagnosis of your PC. If your data matters, back it up before repairs. If the problem continues, a hardware technician can test the parts.

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