Windows BSOD UNMOUNTABLE_BOOT_VOLUME (0x000000ED)

Windows BSOD UNMOUNTABLE_BOOT_VOLUME means Windows cannot mount the boot partition, preventing the system from starting. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Stop code: 0x000000ED — boot volume cannot be mounted. System cannot read the partition containing Windows. Often occurs after BIOS changes or disk configuration changes. Can be triggered by corrupted boot sector or MBR/GPT. More common on systems with multiple drives or dual-boot. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Corrupted boot sector or master boot record (MBR). Changed BIOS settings from AHCI to IDE or vice versa. Failed Windows Update that corrupted boot files. Hard drive cable loose or failing. Disk encryption software conflict. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Boot from Windows installation USB and select Repair your computer > Troubleshoot > Advanced > Command Prompt. Run bootrec /fixmbr, bootrec /fixboot, and bootrec /rebuildbcd. Run chkdsk /r C: to repair the boot volume. Verify BIOS is set to correct SATA mode (AHCI vs IDE) — match what Windows was installed with. Check physical drive connections — reseat SATA cables. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Windows Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.