Fix UNMOUNTABLE_BOOT_VOLUME (0x000000ED) in Windows 7 — Historical Guide

Historical support note: This article targets Windows 7, which reached end of support on January 14, 2020.

UNMOUNTABLE_BOOT_VOLUME is bug check 0x000000ED. Microsoft defines it as a failure by the I/O subsystem to mount the boot volume. File-system corruption, boot-volume problems, storage cabling, or a failing drive can be involved.

If the drive contains important data and is making unusual noises or repeatedly disappearing, stop repair attempts and prioritize data recovery.

1. Enter the Windows 7 recovery environment

Boot from a Windows 7 System Repair Disc or compatible installation media and choose Repair your computer.

Try Startup Repair first when available.

2. Check the file system

Open Command Prompt from recovery options. Confirm the Windows volume letter—it may not be C: in the recovery environment—then run:

chkdsk <drive>: /r

Microsoft specifically lists CHKDSK /r as a possible recovery step for bug check 0xED. It can take a long time and writes repairs to the volume, so do not use it casually on a disk that appears to be physically failing.

3. Try System Restore

If the problem began after a driver, update, or software change, use System Restore from recovery options when a suitable restore point exists.

4. Repair boot records only when indicated

Microsoft also documents boot-record repair as a possible 0xED recovery path. Do not jump straight to rebuilding BCD for every case. If Startup Repair and the file-system check do not resolve the issue, an experienced user can use Windows 7 recovery tools such as bootrec after confirming the system’s boot configuration.

5. Check the storage hardware

If the error returns, run the drive manufacturer’s or PC manufacturer’s storage diagnostics. A failing disk should be replaced rather than repeatedly repaired in software.

Official references

• Microsoft: Bug Check 0xED UNMOUNTABLE_BOOT_VOLUME: https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/bug-check-0xed--unmountable-boot-volume
• Microsoft: CHKDSK: https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/chkdsk
• Microsoft: Windows 7 end-of-support context: https://support.microsoft.com/en-us/servicing/os/windows-7/2020/01/january-14-2020-kb4534310-monthly-rollup