Fixing MBR with gptsync

Question

All of a sudden my Windows 7 bootcamp harddrive couldn&#x60;t be started and I got a „No bootable device -- insert boot disk and press any key“. I tried to restore the partition map with testdisk as this helped me some time ago but I got no luck this time.I installed Windows 10 on a new ssd via the boot camp assistant as a swap for the old bootcamp harrdive. Now I can access the partition but only when I use the boot manager on the startup screen (via alt- key). Otherwise, I still get the „no bootable device“ message or just a blinking cursor.For additional information: I´m using a mac pro 4.1 with a normal pc grafics card, so I am not able to see the the boot screen. This combination worked for me for a long time now and I was switching systems with the Start Volume preference pane.I looked up my problem and tried gptsync on my Macintosh drive (disk0). Now I just want to verify that this tool lists the correct MBR partition table and i can accept its suggestion to fix my booting problems.$ sudo gptsync /dev/disk0Current GPT partition table:#      Start LBA      End LBA  Type1             40       409639  EFI System (FAT)2         409640    487127591  Mac OS X HFS+3      487127592    488397127  Mac OS X BootCurrent MBR partition table:# A    Start LBA      End LBA  Type1              1    488397167  ee  EFI ProtectiveStatus: MBR table must be updated.Proposed new MBR partition table:# A    Start LBA      End LBA  Type1              1       409639  ee  EFI Protective2         409640    487127591  af  Mac OS X HFS+3      487127592    488397127  ab  Mac OS X Boot4      488397128    488397167  ee  EFI ProtectiveMay I update the MBR as printed above? [y/N]gptsync on the bootcamp drive (disk1):$ sudo gptsync /dev/disk1Current GPT partition table:#      Start LBA      End LBA  Type1           2048        34815  MS Reserved2          34816    975794516  Basic Data3      975796224    976771071  UnknownCurrent MBR partition table:# A    Start LBA      End LBA  Type1              1   4294967295  ee  EFI ProtectiveStatus: GPT partition of type &#x27;Unknown&#x27; found, will not touch this disk.Thank you!

Loner T · Answer

Disk0 has no Windows partitions. Can you post the output of sudo gpt -vv -r show /dev/disk1sudo fdisk /dev/disk1diskutil list

cammatej · Answer

$ sudo gpt -vv -r show /dev/disk1Password:gpt show: /dev/disk1: mediasize&#x3D;500107862016; sectorsize&#x3D;512; blocks&#x3D;976773168gpt show: /dev/disk1: PMBR at sector 0gpt show: /dev/disk1: Pri GPT at sector 1gpt show: /dev/disk1: Sec GPT at sector 976773167      start      size  index  contents          0          1        PMBR          1          1        Pri GPT header          2        32        Pri GPT table        34      2014            2048      32768      1  GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE      34816  975759701      2  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7  975794517      1707        975796224    974848      3  GPT part - DE94BBA4-06D1-4D40-A16A-BFD50179D6AC  976771072      2063        976773135        32        Sec GPT table  976773167          1        Sec GPT header$ sudo fdisk /dev/disk1Disk: /dev/disk1    geometry: 60801/255/63 [976773168 sectors]Signature: 0xAA55        Starting      Ending#: id  cyl  hd sec -  cyl  hd sec [    start -      size]------------------------------------------------------------------------1: EE    0  0  2 -  384 254  63 [        1 - 4294967295] &lt;Unknown ID&gt;2: 00    0  0  0 -    0  0  0 [        0 -          0] unused    3: 00    0  0  0 -    0  0  0 [        0 -          0] unused    4: 00    0  0  0 -    0  0  0 [        0 -          0] unused$ diskutil list/dev/disk0 (internal, physical):  #:                      TYPE NAME                    SIZE      IDENTIFIER  0:      GUID_partition_scheme                        *250.1 GB  disk0  1:                        EFI EFI                    209.7 MB  disk0s1  2:                  Apple_HFS Macintosh SSD          249.2 GB  disk0s2  3:                Apple_Boot Recovery HD            650.0 MB  disk0s3/dev/disk1 (internal, physical):  #:                      TYPE NAME                    SIZE      IDENTIFIER  0:      GUID_partition_scheme                        *500.1 GB  disk1  1:        Microsoft Reserved                        16.8 MB    disk1s1  2:      Microsoft Basic Data BOOTCAMP                499.6 GB  disk1s2  3:          Windows Recovery                        499.1 MB  disk1s3

Loner T · Answer

On Disk1, Windows Recovery. It may be easier to create a MBR using GPT FDisk - https://sourceforge.net/projects/gptfdisk/ .GPTSync does not seem to want to handle the disk layout on Disk1 due to the following error.Status: GPT partition of type &#x27;Unknown&#x27; found, will not touch this disk.Also, Disk1 may have been formatted using diskpart.exe without an EFI partition.

Loner T · Answer

Use only 2, since you do not have an EFI partition, and other partitions are not really necessary.

cammatej · Answer

$ sudo gpt -r show /dev/disk0      start       size  index  contents          0          1         PMBR          1          1         Pri GPT header          2         32         Pri GPT table         34          6                  40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B     409640  486717952      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC  487127592    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC  488397128          7           488397135         32         Sec GPT table  488397167          1         Sec GPT header$ sudo fdisk /dev/disk0Disk: /dev/disk0 geometry: 30401/255/63 [488397168 sectors]Signature: 0xAA55         Starting       Ending #: id  cyl  hd sec -  cyl  hd sec [     start -       size]------------------------------------------------------------------------ 1: EE 1023 254  63 - 1023 254  63 [         1 -  488397167] 2: 00    0   0   0 -    0   0   0 [         0 -        0] unused       3: 00    0   0   0 -    0   0   0 [         0 -        0] unused       4: 00    0   0   0 -    0   0   0 [         0 -        0] unused

Loner T · Answer

Leave the 4870 in the MP, remove the MBR, and test booting Windows. Do you still have the WinRE partition?In most cases, the issue is the GPU Firmware which is incompatible with the EFI on the MP? Was macOS update/upgraded to High Sierra when these issues started? The HS EFI updates break previously working configurations, partly due to security fixes and updates.

Loner T · Answer

Can you post the output of sudo gpt -vv -r show o/dev/disk0sudo fdisk /dev/disk0

Loner T · Answer

Use (do not type text like this)sudo gdisk /dev/disk1x (Experts menu)n (New Protective MBR - overwrites Hybrid MBR)p (print GPT)o (print MBR)w (write)y (Confirm write)

cammatej · Answer

Windows Recovery says it can´t do anything. Is it possible that i messed up the installation with the boot camp assistant on the ssd?I assume i had to do the following steps with GPT FDisk:Sudo gdisk /dev/disk1P  (Print list of parts)R  (Recover)H (chooses Hybrid)O (print current Hybrid MBR)Partitions numbers to be hybridized: 2 3 4Y  (Good for GRUB question)N  (part 2 boot flag)N  (part 3 boot flag)Y  (part 4 boot flag make NTFS bootable partition)O  (print current Hybrid MBR)W (Write the new MBR)Y (Yes! write the new MBR)RebootWhat would my partition numbers be?

cammatej · Answer

I did the steps below but now I can&#x60;t boot windows anymore. I tried windows recovery and chkdsk. I do see the bootcamp partition in macOS.$ sudo gdisk /dev/disk1Password:GPT fdisk (gdisk) version 1.0.3Warning: Devices opened with shared lock will not have theirpartition table automatically reloaded!The protective MBR&#x27;s 0xEE partition is oversized! Auto-repairing.Partition table scan:  MBR: protective  BSD: not present  APM: not present  GPT: presentFound valid GPT with protective MBR; using GPT.Command (? for help): pDisk /dev/disk1: 976773168 sectors, 465.8 GiBSector size (logical): 512 bytesDisk identifier (GUID): D40C269E-E4C0-4CB2-B655-29E3309F4BF8Partition table holds up to 128 entriesMain partition table begins at sector 2 and ends at sector 33First usable sector is 34, last usable sector is 976773134Partitions will be aligned on 2048-sector boundariesTotal free space is 5784 sectors (2.8 MiB)Number  Start (sector)    End (sector)  Size       Code  Name   1            2048           34815   16.0 MiB    0C01  Microsoft reserved ...   2           34816       975794516   465.3 GiB   0700  Basic data partition   3       975796224       976771071   476.0 MiB   2700 Command (? for help): rRecovery/transformation command (? for help): hWARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,just hit the Enter key at the below prompt and your MBR partition table willbe untouched.Type from one to three GPT partition numbers, separated by spaces, to beadded to the hybrid MBR, in sequence: 2Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): yCreating entry for GPT partition #2 (MBR partition #2)Enter an MBR hex code (default 07):Set the bootable flag? (Y/N): yUnused partition space(s) found. Use one to protect more partitions? (Y/N): nRecovery/transformation command (? for help): oDisk size is 976773168 sectors (465.8 GiB)MBR disk identifier: 0x00000000MBR partitions:Number  Boot  Start Sector   End Sector   Status      Code   1                     1        34815   primary     0xEE   2      *          34816    975794516   primary     0x07Recovery/transformation command (? for help): wFinal checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTINGPARTITIONS!!Do you want to proceed? (Y/N): yOK; writing new GUID partition table (GPT) to /dev/disk1.Warning: Devices opened with shared lock will not have theirpartition table automatically reloaded!Warning: The kernel may continue to use old or deleted partitions.You should reboot or remove the drive.The operation has completed successfully.

cammatej · Answer

The WinRE is still there but could´t fix the problems, same with booting from windows usb stick. I did not upgrade to high sierra and I dont think there was a security patch before the problem occured. I used to wait for new nvidia web drivers befor I install macOS patches.How do i remove the MBR?

cammatej · Answer

Still can´t boot windows, got a blinking cursor. The bootcamp partition shows up in the start volume settings but in the boot menu via alt-key there is only the WinRE partition which fails to repair windows.

Loner T · Answer

You have a Windows RE. When did Windows last boot?Are you able to install the standard macOS GPU and boot into Windows?

cammatej · Answer

I last booted into windows yesterday with the standard GPU (HD 4870). After the use of gdisk the boot failed.

Loner T · Answer

Do you have Windows Automatic Updates enabled? Have you applied a recent AMD GPU update? Do you have a Windows System Restore point.

Fixing MBR with gptsync

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