~30% – but when it works, you're done in 5 minutes.
diskpart list volume exit Look for the volume labeled or System Reserved . Often the OS drive is D: in recovery mode (because the recovery environment uses C: for itself). Note the drive letter (e.g., D:). Step 4.3 – Rebuild Boot Configuration Data (BCD) This fixes 80% of boot errors:
For deeper corruption:
bootsect /nt60 sys /mbr Then retry /fixboot . If /rebuildbcd doesn't find any OS, rename the old BCD and create a new one:
From Command Prompt:
sfc /scannow /offbootdir=D:\ /offwindir=D:\Windows (Replace D: with your OS drive letter.)
bcdedit /export C:\BCD_Backup attrib C:\boot\bcd -s -h -r ren C:\boot\bcd bcd.old bootrec /rebuildbcd (Replace C: with your system reserved partition – often a small 350MB partition without a drive letter. Use diskpart → list volume → select volume X → assign letter=S: → exit then S: for the commands above.) If your server uses BIOS (not UEFI) and you see "Operating system not found": windows server 2012 r2 boot repair
Startup Repair scans for missing/corrupt boot files, registry damage, and driver issues, then attempts auto-fix.
Published by: TechAdmin Solutions Difficulty: Intermediate/Advanced Estimated Time: 30–60 minutes ~30% – but when it works, you're done in 5 minutes
Have a unique boot error not covered here? Drop a comment below or reach out on our forums. Last updated: March 2025 Compatible with: Windows Server 2012 R2 Standard, Datacenter, Essentials, and Foundation
From Command Prompt (recovery environment): Note the drive letter (e