Comprehensive Guide to Windows Server 2012 R2 Boot Repair A server that refuses to boot is a critical emergency. When Windows Server 2012 R2 fails to start, it often displays a black screen, a blue screen (BSOD), or errors like "Operating System not found" or "Bootmgr is missing."
From the options screen, select Troubleshoot , then Command Prompt . Phase 2: Fixing the Boot Configuration Data (BCD) and MBR
Before diving into advanced recovery tools, a simple but often effective step is to try the (LKGC). This option starts your server using the last registry and driver configuration that successfully booted the system. It is useful for undoing recent driver installations or registry changes that caused the boot failure. To access it, restart your server and repeatedly press the F8 key before the Windows logo appears. From the Advanced Boot Options menu, select "Last Known Good Configuration (advanced)". windows server 2012 r2 boot repair
Scenario B — UEFI system fails to boot after disk replacement
Navigate to > Advanced Options > Command Prompt . 2. Repairing the Boot Sector (MBR/Legacy) Comprehensive Guide to Windows Server 2012 R2 Boot
copy d:\windows\system32\config\regback\default . copy d:\windows\system32\config\regback\sam . copy d:\windows\system32\config\regback\security . copy d:\windows\system32\config\regback\software . copy d:\windows\system32\config\regback\system .
Assign a drive letter to it so you can access it by typing assign letter=Z . Exit Diskpart by typing exit . This option starts your server using the last
Press any key when prompted to boot from the CD/DVD or USB.
On newer updates of Server 2012 R2, running bootrec /fixboot can trigger an "Access is denied" error. If this happens on an MBR setup, use the boot sector code update utility to re-register the system boot structure: bootsect /nt60 sys /force Use code with caution. After executing this, retry your bootrec /fixboot routine. Summary Reference Table Boot Issue Partition System Remediation Step / Black Screen Legacy BIOS / MBR bootrec /fixmbr →right arrow bootrec /fixboot →right arrow bootrec /rebuildbcd EFI Boot Error / Missing Boot Device UEFI / GPT Assign letter to FAT32 partition →right arrow Run bcdboot C:\Windows /s S: /f UEFI Infinite Recovery / Boot Loops
This indicates the BCD store exists but is deeply corrupted. You must back up the old BCD, delete it, and force a fresh rebuild. Step 3: Manual BCD Rebuild (For Scenario B)
Before attempting repair, it is crucial to recognize typical culprits: