After doing a System Restore on my Win10 machine last night I went to sleep, and woke up to some alarming news; my machine wouldnt even boot.
Problem:
After a failed System Restore attempt (original error: System Restore did not complete successfully… 0x80070780, involving a file under an old user profile “MIke_2020”), the system now fails to boot entirely with 0xc0000001 (“Your PC couldn’t start properly”). Goes straight to this error, no Windows logo.
Troubleshooting performed, in order:
Online chkdsk (chkdsk /scan from within a live session) failed with: “A snapshot error occurred while scanning this drive… run an offline scan and fix.” — pointed to a Volume Shadow Copy (VSS) issue.
Booted from Windows 10 recovery USB. Used diskpart -> list volume to identify correct OS drive (D: in this environment, “Windows 10” label, 1907 GB) vs. other unrelated data drives.
Offline chkdsk on correct drive:
chkdsk D: /f /r
Result: 0 KB bad sectors, fixed file system errors, “Windows has made corrections to the file system. No further action required.”
Boot repair attempts:
bootrec /fixmbr -> success
bootrec /fixboot -> Access denied
Diagnosed as EFI System Partition lacking a drive letter. Used diskpart -> select volume 3 (the 100MB FAT32 hidden EFI partition) -> assign letter=Z
Ran: bcdboot D:windows /s Z: /f UEFI -> “Boot files successfully created.”
Verified boot config:
bcdedit /enum — Boot Manager and Boot Loader entries both correct, pointing to right partition and Windowssystem32winload.efi.
System file check:
sfc /scannow /offbootdir=D: /offwindir=D:Windows -> “Windows Resource Protection did not find any integrity violations.”
Checked D:WindowsSystem32configRegBack — empty (normal for Win10 default config, not the cause).
Checked BIOS: Secure Boot already disabled; CSM disabled; confirmed “Windows Boot Manager” entry present in boot list.
Ran Startup Repair (from recovery menu, twice, on separate occasions) both times failed with identical result in D:WindowsSystem32LogFilesSrtSrtTrail.txt:
Bugcheck c000021a. Parameters = 0xfffffcd8472d4c150,
0xfffffffffc0000428, 0xfffffcd847242f410, 0x0. Boot critical file is
corrupt.
Repair action: File repair Failed. Error code = 0x57
Repair action: System files integrity check and repair Failed. Error code = 0x57
Manual boot file replacement attempt:
Booted from Windows 10 installation USB (not just recovery)
Located install media: H:sourcesinstall.esd
Listed editions: dism /Get-WimInfo /WimFile:H:sourcesinstall.esd -> confirmed Windows 10 Pro = Index 6
Exported that edition:
dism /Export-Image /SourceImageFile:H:Sourcesinstall.esd /SourceIndex:6 /DestinationImageFile:C:pro.wim /Compress:max /CheckIntegrity
-> success (landed on C:, a separate personal data drive, not intentionally)
Mounted the image:
dism /Mount-Wim /WimFile:C:pro.wim /index:1 /MountDir:D:mount
(initial attempts to mount with /ReadOnly and to X:mount both failed with Error 5: Access denied; running dism /Cleanup-Mountpoints first, then mounting without /ReadOnly to a folder on D: instead of X:, finally succeeded)
Copied the file: copy D:mountWindowsSystem32winload.efi D:WindowsSystem32winload.efi /y -> “1 file copied”
Unmounted cleanly: dism /Unmount-Wim /MountDir:D:mount /Discard -> success
Deleted temp file: del C:pro.wim
Result after all of the above: Rebooted with USB removed / boot order changed to internal drive first. Still fails identically; either straight to 0xc0000001, or hangs indefinitely on motherboard splash screen with no disk activity indication, sometimes eventually landing on the same blue 0xc0000001 screen before auto-rebooting.
Also noted: “Reset this PC” option is not available in Advanced Options when booted from install media (only appears when booting recovery from the actual installed Windows recovery partition, which isn’t accessible since Windows won’t boot). “Upgrade: keep files and apps” install option is blocked when Setup is run from bootable media (Microsoft restriction — only works launching Setup from within a live Windows session).
Question for community:
What else causes Bugcheck c000021a (error 0x57 on repair) when disk health, boot configuration, and SFC all check out clean, and manually replacing the flagged file with a fresh copy from official install media doesn’t resolve the boot failure?
System:
Gigabyte AORUS X570 I Pro WiFi, Ryzen 9 3900X, multiple drives (Windows drive shows as D: in recovery environment, normally C: on normal boot. Confirmed via diskpart/list volume, labeled “Windows 10,” NTFS, ~1907 GB).
