UNMOUNTABLE_BOOT_VOLUME (0xED): Causes and Fixes

UNMOUNTABLE_BOOT_VOLUME (0x000000ED)

Stop code 0x000000ED, also written 0xED. 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

Windows found the boot drive but could not mount its file system.

What UNMOUNTABLE_BOOT_VOLUME means

Unlike INACCESSIBLE_BOOT_DEVICE, Windows can reach the drive here but cannot mount the file system on it. File system damage, a failing drive and connection problems are the usual causes, and an unexpected power loss during a write can leave the volume in a bad state.

Common causes

File system corruption on the Windows volume
A failing drive with bad sectors
A loose or damaged SATA cable or M.2 connection
Damaged boot data after an interrupted update or power loss

How to fix UNMOUNTABLE_BOOT_VOLUME

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

Back up before repairs. If the files matter, connect the drive to another PC (a USB enclosure works) or boot a recovery environment and copy what you need first. File system repairs can remove damaged data.
Run Startup Repair. From the recovery menu choose Troubleshoot, Advanced options, Startup Repair and let it finish.
Repair the file system. In Advanced options open Command Prompt, confirm which drive letter holds Windows, then run chkdsk X: /f with that letter. Let it run to completion.
Reseat or replace the cable. Power off, unplug the PC and reseat the data cable or M.2 drive. A new SATA cable is cheap and rules out a common cause.
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.

When to stop and protect your data

If chkdsk reports many bad sectors or the SMART data is poor, replace the drive and restore from backup rather than repairing it repeatedly.

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 start-up and boot errors

INACCESSIBLE_BOOT_DEVICE (0x7B)

Frequently asked questions

What does UNMOUNTABLE_BOOT_VOLUME mean?

Windows found the boot drive but could not mount its file system. Unlike INACCESSIBLE_BOOT_DEVICE, Windows can reach the drive here but cannot mount the file system on it. File system damage, a failing drive and connection problems are the usual causes, and an unexpected power loss during a write can leave the volume in a bad state.

What usually causes UNMOUNTABLE_BOOT_VOLUME?

Typical causes: File system corruption on the Windows volume; A failing drive with bad sectors; A loose or damaged SATA cable or M.2 connection; Damaged boot data after an interrupted update or power loss.

How do I fix UNMOUNTABLE_BOOT_VOLUME (0x000000ED)?

A sensible order is: 1) Back up before repairs; 2) Run Startup Repair; 3) Repair the file system; 4) Reseat or replace the cable. If chkdsk reports many bad sectors or the SMART data is poor, replace the drive and restore from backup rather than repairing it repeatedly.

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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