How to Fix the INACCESSIBLE_BOOT_DEVICE Error
A clear, up-to-date walkthrough for Windows 10 and 11 — the fixes that actually work, and the one mistake that can cost you your files for good.
Few things make your stomach drop like restarting your PC and getting a blue screen that reads INACCESSIBLE_BOOT_DEVICE. It looks catastrophic, and once in a while it is — but in the fifteen-plus years I've been running Dave's Computers here in Somerville, most machines that come in with this error leave working, often without losing a single file.
The catch is figuring out which version of the problem you have before you start changing things. INACCESSIBLE_BOOT_DEVICE has half a dozen common causes, and a couple of the "fixes" floating around the internet will actively make things worse if your drive is the part that's failing. So we'll start with what the error means, work from the safest steps to the riskier ones, and I'll be straight with you about the point where you should stop and let a lab image the drive instead of pushing your luck.
What the INACCESSIBLE_BOOT_DEVICE error actually means
INACCESSIBLE_BOOT_DEVICE is a Windows stop error, usually shown with the code 0x0000007B (sometimes written 0x7B). In plain English: during startup, Windows reached the point where it needs to mount the drive that holds your operating system — and it couldn't. The kernel loaded, asked for the boot volume, and got back nothing it could read.
That "couldn't read the boot drive" can come from software (a driver, the boot records, file-system corruption) or from hardware (a cable, a controller setting, or a drive that's genuinely dying). The screen looks identical in every case, which is exactly why people guess wrong. The good news is that a short process of elimination tells you which camp you're in.
The causes we actually see on the bench
Here's how these break down in real life at the shop, roughly most common to least:
- A bad Windows update or storage driver. This is the number-one trigger by a wide margin. A cumulative or feature update installs a storage driver that doesn't agree with your hardware, and the next reboot can't load the disk. If the machine was fine yesterday and threw this right after an update, start here.
- A changed storage-controller mode in the BIOS/UEFI. Windows installs itself expecting a specific disk mode — almost always AHCI (or RAID, if you actually run Intel RST). If a BIOS update, a cleared CMOS, or a well-meaning tweak flips that setting, you get 0x7B instantly. (This is where some outdated advice tells you to switch to "IDE" mode — don't. On a modern Windows install that's a great way to create this error, not fix it.)
- Corrupt boot files or file-system damage. The Boot Configuration Data (BCD) gets damaged, or the file system on the Windows partition has errors after a bad shutdown, power loss, or interrupted update.
- A failing drive. Bad sectors, a dying SSD or NVMe, a loose or failing SATA/power cable, or an NVMe that's lost its link. This is the bucket that puts your data at risk, and it's why the order of operations below matters.
- Recently changed or cloned hardware. Moving a Windows drive into a different machine, or cloning to a new SSD without prepping it, often lands here because the new chipset needs drivers the old install never loaded.
How to fix INACCESSIBLE_BOOT_DEVICE (safest steps first)
Work down this list in order and retest after each step. The moment the machine boots normally, stop — there's no need to keep going. And before you start: if there's anything on this computer you can't replace and don't have backed up, read the warning section below first. Some of these steps are safe on a healthy drive but risky on a failing one.
1. Get into the Windows Recovery Environment (WinRE)
Most of these fixes run from WinRE. If Windows won't start, power the machine off during the boot logo three times in a row and it'll usually offer Automatic Repair → Advanced options. If that doesn't work, boot from a Windows installation USB (made on another PC with Microsoft's Media Creation Tool) and choose Repair your computer, not Install.
2. Uninstall the most recent update
Because a bad update is the most common cause, this is the highest-value first move. In WinRE go to Troubleshoot → Advanced options → Uninstall Updates and remove the latest quality update (or the latest feature update, if that's what landed right before the problem). Reboot and retest.
3. Run Startup Repair
Still in Advanced options, choose Startup Repair. It's automated, low-risk, and quietly fixes a lot of boot-record and BCD problems on its own.
4. Check the storage mode in your BIOS/UEFI
Reboot into your BIOS/UEFI (usually Del, F2, or F10 at startup) and find the SATA/storage configuration. If it was recently changed, set it back to what Windows expects — for the vast majority of systems that's AHCI, or RAID only if you genuinely run an Intel RST array. Make sure the drive with Windows on it is listed and set as the boot device. If the drive isn't listed at all, that points at hardware — skip to step 8.
5. Repair the boot records
From a WinRE command prompt, the classic sequence is:
bootrec /scanos
bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcdOn newer UEFI/GPT systems /fixboot sometimes returns "Access is denied" — that's normal, and the fix is to rebuild the EFI partition with bcdboot. If you're not comfortable at this level, this is a good place to bring it in.
6. Force the right storage driver (the StartOverride fix)
This is the proper version of the "BIOS mode" fix. From WinRE you load the offline SYSTEM registry hive and set the Start value to 0 for the storage driver your system actually uses — storahci for AHCI, stornvme for NVMe drives, or iaStorV / iaStorAVC for Intel RAID. That forces Windows to load the correct disk driver at boot. It's effective, but editing an offline registry is easy to get wrong, so go slowly — or hand it to us.
7. Repair system files (DISM + SFC)
From the WinRE command prompt, run DISM and then SFC against your offline Windows installation to repair corrupted system components. This catches cases where a botched update left the system files inconsistent.
8. Check the drive itself — and run chkdsk carefully
chkdsk /f /r on your Windows volume will find and try to repair file-system errors and bad sectors. On a healthy drive that's fine. On a failing drive, a full /r pass hammers it for hours and can be the straw that breaks it — so first confirm the drive is actually healthy: is it detected in the BIOS? Is it clicking or making noises? Were there SMART warnings? If any of that is true, don't run chkdsk yet (see the warning below).
9. Clean install — last resort, and only when the drive is confirmed healthy and your data is safe
If the drive checks out, the data's backed up (or recovered), and nothing above worked, a clean install of Windows clears out whatever software gremlin caused it. This wipes the drive, so it's genuinely the last step — never the first.
Read this first When to stop and protect your data
This is the part most guides leave out, because the honest advice doesn't keep you clicking through their steps. Here it is anyway:
If your important files aren't backed up and there's any sign the drive is failing — it's not detected in the BIOS, it's clicking or buzzing, it threw SMART warnings, or chkdsk is turning up piles of bad sectors — stop running repairs. Every reboot and every chkdsk pass puts stress on a dying drive, and I've seen plenty of cases where "just one more repair attempt" turned a fully recoverable situation into an unrecoverable one.
When a drive is on its way out, the right first move isn't repair — it's to image the drive (make a sector-by-sector clone) and do any further work on the copy. That's exactly what a proper data recovery process does, whether it's a hard drive or an SSD. If you're not sure which situation you're in, that uncertainty by itself is a good reason to bring it in before you do anything else — a wrong guess here is the one mistake you can't undo.
How much does it cost to fix an INACCESSIBLE_BOOT_DEVICE error?
I can't quote a boot error blind, because the same screen can mean a five-minute driver rollback or a failing drive that needs recovery — and those are very different jobs. What I can tell you is how our pricing works.
No surprises, and nothing gets done without your okay after the diagnostic. Here's how our diagnostic works if you'd like the details.
Frequently asked questions
Is INACCESSIBLE_BOOT_DEVICE a hardware or software problem?
It can be either, which is what makes it tricky. Most often it's software — a bad update or driver — but it can also be a BIOS setting or a failing drive. The troubleshooting steps above are designed to tell the two apart before you commit to anything drastic.
Will I lose my files if I get this error?
Usually not. If the cause is a driver, a BIOS mode, or corrupt boot records, your data is sitting safely on the drive and a repair leaves it untouched. The real risk is when the drive itself is failing — and even then, the files are often recoverable as long as you stop stressing the drive and have it imaged.
Can I fix it without reinstalling Windows?
In most cases, yes. Uninstalling a bad update, correcting the storage mode, repairing the boot records, or forcing the right disk driver all fix the problem without wiping anything. A clean install should be the last resort, not the first thing you try.
Why did INACCESSIBLE_BOOT_DEVICE show up right after a Windows update?
Because that's the most common trigger there is. An update can install a storage driver that doesn't match your hardware, and the next boot can't read the disk. Uninstalling the most recent update from the recovery environment fixes a large share of these.
Should I run chkdsk to fix it?
Only if you're confident the drive is healthy. On a good drive, chkdsk /f /r is a reasonable repair step. On a drive that's already failing, a full chkdsk can finish it off — so check that the drive is detected and behaving first, and if in doubt, image it before running anything.
Does this error mean my SSD or hard drive is dead?
Not necessarily — most of the time it's software or a setting. But if the drive isn't showing up in the BIOS, or it's making noises, that's a real warning sign. If your data isn't backed up at that point, treat it as a recovery situation, not a repair one.
How much does it cost to have you fix it?
It starts with a $75 diagnostic that's credited toward the repair. Boot- and software-level fixes are a flat fee we quote after diagnosis; data recovery, if needed, starts at $199. See the pricing section above for the details.
Do you offer remote or in-home service for this?
For a machine that won't boot, no — and honestly, it couldn't be done remotely anyway, since there's nothing to connect to until it starts. This is a drop-off repair: bring it to our Somerville shop and we'll take it from there.
Stuck, or want it handled right the first time?
Bring your computer to Dave's Computers in Somerville and we'll find out exactly what's behind the INACCESSIBLE_BOOT_DEVICE error — and tell you straight whether it's a quick fix or a drive that needs rescuing.
- 75 N Bridge St, Somerville, NJ 08876 (behind Bank of America)
- Hours: Mon-Fri 10am-5pm, Sat 9am-2pm
- Phone: 908-428-9558
- Proudly serving Somerset, Middlesex, Hunterdon & Mercer counties