This question already has an answer here:

I know many people have had similar kind of issues and I tried to fix this with the answers I found but with no luck.

  • Device: iMac 27" mid 2011
  • OS: Latest High Sierra (I think the recovery mode is maybe the Lion version?)

I have Linux partition with High Sierra, and been using it with no problems at all. Now I did a Bootcamp partition too and installed Windows 7. After that, I am now unable to boot to Mac and in recovery mode I can see that the main partition type is now FFFFFF-FFFF...

The partitions in a nutshell are like:

  • High sierra, ~850 GB
  • Linux, ~100 GB <- This can be deleted
  • Bootcamp, ~49 GB <- This can be deleted

What I have tried:

I did the gpt destroy disk0 and after that added all the volumes back with

gpt create -f disk0

gpt add -i 1 -b 40 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk0

gpt add -i 2 -b 409640 -s 1662109312 -t 7C3457EF-0000-11AA-AA11-00306543ECAC /dev/disk0

and so on.. then then trying to verify the volumes with diskutil verityVolume disk0s2 I get "Error starting file system verification for disk0s2: Unrecognized file system (-69846)"

Now I am at the point where I do not know what to do anymore.

Where I started:



And where I am now:


enter image description here

  1. I just want a easiest way to get MacOS back to working with the data that's in there if possible and all the other partitions are disposable.

  2. Or I would like to know how to just format the drive and remove all the partitions so I can do a clean install (plan B).

All comments appreciated! Thanks!

Edit1: Oops I forgot that of course I can just format the drive via the graphical disk utility tool.

marked as duplicate by David Anderson, nohillside Jul 14 at 15:34

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Plan B - open Disk Utility from recovery mode and blow it all away – goofology Jul 14 at 7:21
  • @goofology Please avoid answering in comments and consider writing a proper answer post. "All comments appreciated" was not to be taken literally. – ankii Jul 14 at 7:46
  • @ankiiiiiii I disagree with your advice. My comment was useful, but not worthy of a "proper answer", as it does not address both of OP's questions, and it is likely something OP is already aware of or could easily find, as he has clearly already found his way into recovery mode. Not to mention, OP's literal "comments appreciated...". Please avoid critiquing helpful comments and consider adding value to the conversation instead. – goofology Jul 14 at 8:38
  • @goofology You can definitely write an answer specifically for part 2 as OP gave a choice. They want to know how to format and do a clean install. – ankii Jul 14 at 8:43
  • @ankiiiiiii I'm aware that I could submit an answer, but 1, it's not properly helpful to the OP's primary desired outcome, and 2, it's stupidly simple and not deserving of an "award" in my opinion, thus unworthy to post as an answer. Put another way, it's a "freebie" - I wouldn't charge a client for explaining they simply need to click on the "Disk Utility" button that's staring them in the face. I appreciate your intent to ensure quality answers, but in this case, my contribution, while useful, does not meet the 'quality bar'. – goofology Jul 14 at 9:08

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