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so I had installed Bootcamp and felt the need of getting more space. So I created a free partition inside mac and went on to delete it in Windows.

Well, turned out that after I deleted a partition that was around 200mb big, the mac partition wouldnt show up as a viable booting option when trying to boot while holding alt. Only the windows partition would show up.

My mac osx partition with all my data is still on my hard drive. I tried looking up resolutions on the internet, but most answers are from older versions of os x and suggest reinstalling.

As I am not an expert on this topic I have included some screenshots of my partitions. My guess is, that I accidently deleted the boot partition. Any help on how to recover this issue is appreciated :) Preferable I wouldnt want to reinstall.

I know that there are other threads talking about the same issue, but since I really have no knowledge about this topic whatsoever I am not sure if I am really experiencing the same issue as f.x. this thread: Accidently deleted some small sized partitions when installing Windows. OSX Partition wont boot

I would follow the guide described in this thread if someone could confirm that its the same issue. gpt -r show /dev/disk0 and fdisk /dev/disk0 diskutil list

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Usually the main macOS partition (disk0s2) is followed by a Recovery HD which is required as second boot stage for particular macOS partitions.

The recovery partition has a standard size of 1269536 512-blocks (or 158692 4096-blocks on 4k disks) and the partition type 426F6F74-0000-11AA-AA11-00306543ECAC. If your attempt to resize/delete macOS partitions from inside Windows (BTW that's a big

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didn't screw the partition map somehow or erase/overwrite former blocks of the Recovery HD it should be recoverable by simply adding its probable partition map entry.

  • Boot to Internet Recovery Mode
  • Open in the menubar > Utilities > Terminal
  • get some details:

    diskutil list #below I assume the disk identifier of the internal disk is disk0
    gpt -r show disk0
    
  • Unmount disk0:

    diskutil umountDisk disk0
    
  • add the recovery partition:

    gpt add -i 4 -b 54478096 -s 1269536 -t 426F6F74-0000-11AA-AA11-00306543ECAC disk0
    
  • verify disk and recovery partition:

    diskutil list #get the disk identifier of the "new" 650.0 MB partition
    diskutil verifyDisk disk0       
    diskutil verifyVolume disk0sX #use the disk identifier of the "new" 650.0 MB partition (probably disk0s3 or disk0s4)
    

If you get:

The volume Recovery HD appears to be OK
Finished file system verification on disk0sX Recovery HD

from the last command everything is OK and your Mac should boot properly.

Otherwise you have to restore the Recovery HD from scratch or copy it from a Mac with the same system version.

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