Stuck at a blue screen or a black screen with a hex code? Find your stop code below for the one-line cause and the exact fix. Most boot errors are repaired from Windows Recovery (WinRE) — reach it by forcing three failed boots, or by booting from a Windows install USB and choosing Repair your computer.
format, clean, or a reinstall to "get past" an error — that destroys data, especially on BitLocker-encrypted drives.
| Stop code | Likely cause | Fix |
|---|---|---|
| INACCESSIBLE_BOOT_DEVICE 0x0000007B |
Wrong SATA mode (AHCI/RAID), missing storage driver, or bad update broke the boot path. | Exact fix → |
| 0xc000000e | BCD points to a boot volume Windows can't reach. On UEFI, bootrec /fixboot says "Access denied". |
Exact fix → |
| 0xc0000225 | winload.efi missing/corrupt — EFI boot files damaged, often after a clone or partition change. |
Exact fix → |
| BitLocker recovery loop | An update changed TPM/Secure Boot measurements; BitLocker keeps prompting for the recovery key. | Exact fix → |
| 0xc0000001 | Corrupt registry or unreadable BCD/SAM; Windows can't read boot data. | Exact fix → |
| 0xc000014c | BCD store is missing, corrupt, or unreadable — often after power loss during a write. | Exact fix → |
| 0xc0000034 | BCD missing required boot entry — common after a failed/interrupted Windows update. | Exact fix → |
| CRITICAL_PROCESS_DIED 0x000000EF |
A critical Windows process crashed — corrupted system files, a bad driver, or disk errors. | Exact fix → |
| UNMOUNTABLE_BOOT_VOLUME 0x000000ED |
Windows can't mount the boot volume — file-system corruption, a failing drive or cable, or a bad update (confirmed with the January 2026 KB5074109 update). | Exact fix → |
| Automatic Repair loop Preparing Automatic Repair / Diagnosing your PC |
Corrupted system files, failed update, bad driver, or disk errors — Windows keeps restarting into its own repair tool. | Exact fix → |
| SrtTrail.txt Startup Repair failure log |
Startup Repair ran and failed — corrupted system files, a bad update, a damaged driver, or disk errors broke the boot path. | Exact fix → |
| BOOTMGR is missing Press Ctrl+Alt+Del to restart |
Wrong boot device, inactive System Reserved partition, corrupted MBR or boot sector, or damaged \Boot\BCD store. |
Exact fix → |
| Operating system not found Missing operating system |
Firmware found no bootloader — wrong boot device, drive not detected, UEFI/Legacy mode mismatched to the disk, or damaged MBR/BCD. | Exact fix → |
| A disk read error occurred Press Ctrl+Alt+Del to restart |
Early boot code couldn't read the drive — failing disk, loose cable, corrupted MBR/boot sector, bad clone, or faulty RAM. | Exact fix → |
| Reboot and select proper boot device | Wrong boot order, disconnected drive, UEFI/Legacy mode mismatch, or corrupted boot records — firmware can't find a bootable partition. | Exact fix → |
| No bootable device found | Wrong boot order, USB device hijacking boot, UEFI/Legacy mode mismatch, loose drive cable, or dead CMOS battery — firmware can't find a bootable partition. | Exact fix → |
| Start PXE over IPv4 Checking Media Presence |
Wrong boot order (network/PXE ranked above the internal drive), drive not detected, corrupted boot records, or UEFI/Legacy mode mismatch — firmware falls through to network boot. | Exact fix → |
| Secure Boot Violation Invalid Signature Detected |
Stale or corrupted Secure Boot keys, damaged EFI boot files, outdated firmware, or an unsigned bootloader in the boot path. | Exact fix → |
| BitLocker recovery after BIOS update TPM PCR mismatch after firmware update |
A BIOS or UEFI firmware update changed TPM boot measurements (PCR values); BitLocker sees the change as tampering and demands the recovery key. | Exact fix → |
| STATUS_SYSTEM_PROCESS_TERMINATED 0xc000021A |
A critical process (winlogon.exe or csrss.exe) crashed — corrupted system files, a failed update, or an incompatible third-party program. |
Exact fix → |
| 0xc000000f | Boot Manager can't read the BCD or a file it points to — corrupt boot store after power loss or a failed update, wrong boot device, or a failing drive. | Exact fix → |
| 0xc00000e9 | "An unexpected I/O error has occurred" — Boot Manager couldn't read \Boot\BCD or winload.efi. Usually a loose cable, a failing drive, or a USB device pulled mid-use; sometimes corrupt boot files. |
Exact fix → |
| 0xc0000098 | BCD store is readable but holds no valid Windows entry — usually after power loss, a disk write error, or manual boot/partition changes. | Exact fix → |
| 0xc0000185 | "A required device isn't connected or can't be accessed" — the boot disk reported an I/O error. Usually a failing or read-only drive or a loose cable; sometimes a corrupt BCD. | Exact fix → |
| winload.exe missing or corrupt 0xc000000f / 0xc0000225 |
Legacy BIOS loader \Windows\system32\winload.exe can't load — usually a corrupt BCD or one pointing at the wrong partition after a clone, partition change, or forced shutdown. |
Exact fix → |
| \Windows\System32\config\SYSTEM missing or corrupt System registry file is missing or contains errors |
The SYSTEM registry hive is damaged or wasn't closed correctly — usually an unclean shutdown, disk errors, or an interrupted update. Not a BCD problem, so bootrec won't fix it. |
Exact fix → |