Start-up and boot errors

INACCESSIBLE_BOOT_DEVICE (0x0000007B)

Stop code 0x0000007B, also written 0x7B. 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 could not read the drive it boots from during start-up.

What INACCESSIBLE_BOOT_DEVICE means

During start-up Windows needs a working driver and a readable system drive. This stop appears when the storage controller mode or driver changes, the drive is not detected or failing, or the file system or boot data is damaged.

Common causes

A BIOS or UEFI change to the storage mode (AHCI, RAID, Intel RST or VMD), including a BIOS reset or update
A cloned or moved drive that Windows has no matching driver for
A failing drive or a loose cable or connector
File system or boot configuration damage after a failed update or power loss

How to fix INACCESSIBLE_BOOT_DEVICE

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

Undo recent BIOS changes. If the stop began after a BIOS update, reset or change, enter the BIOS and restore the original storage mode. Changing the mode on a PC that was installed under a different one can cause exactly this error, and switching back often fixes it.
Confirm the drive is detected. Check that the system drive appears in the BIOS or UEFI storage list. If it is missing, power off, reseat the SATA or M.2 connection and test again.
Run Startup Repair. From the recovery menu choose Troubleshoot, Advanced options, Startup Repair. It can fix boot configuration problems without touching your files.
Check the file system from recovery. In Advanced options open Command Prompt and confirm which drive letter holds Windows (letters can differ in recovery), then run chkdsk X: /f with that letter in place of X. Back up first if you can, because repairs on a failing drive can make things worse.

When to stop and protect your data

If the drive is missing from the BIOS, makes clicking noises, or reports serious SMART warnings, stop repair attempts and recover your files first.

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

UNMOUNTABLE_BOOT_VOLUME (0xED)

Frequently asked questions

What does INACCESSIBLE_BOOT_DEVICE mean?

Windows could not read the drive it boots from during start-up. During start-up Windows needs a working driver and a readable system drive. This stop appears when the storage controller mode or driver changes, the drive is not detected or failing, or the file system or boot data is damaged.

What usually causes INACCESSIBLE_BOOT_DEVICE?

Typical causes: A BIOS or UEFI change to the storage mode (AHCI, RAID, Intel RST or VMD), including a BIOS reset or update; A cloned or moved drive that Windows has no matching driver for; A failing drive or a loose cable or connector; File system or boot configuration damage after a failed update or power loss.

How do I fix INACCESSIBLE_BOOT_DEVICE (0x0000007B)?

A sensible order is: 1) Undo recent BIOS changes; 2) Confirm the drive is detected; 3) Run Startup Repair; 4) Check the file system from recovery. If the drive is missing from the BIOS, makes clicking noises, or reports serious SMART warnings, stop repair attempts and recover your files first.

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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