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I'm having a similar issue with this (MacOS partition formatted FFFFFFF etc after bootcamp install), but I got confused while reading the comments.

I thought it would be a great idea to dualboot Catalina and Mavericks on my laptop, and I already had a Bootcamp-ed Windows 10 partition that was unused, so I wiped that, installed Mavericks, all went fine until it restarted and my Catalina partition didn't show up in the boot picker.

I assumed it was just simply because Mavericks has no idea what APFS is - it just showed up in Disk Utility as "disk0s2". I created a Catalina installer, booted into its disk utility and it doesn't even show up, until you go to the partition menu.

As I said earlier, I got lost unfortunately with all of the guides. Any help is greatly appreciated, especially for keeping the data in disk0s2 intact.

This is what gpt -rf show disk0 gives me: enter image description here

It's this classic FFFFFFFFF partition type again.

chirusayok9
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  • If you want to know the exact commands to enter, then boot to the Catalina installer and enter the command gpt -rf show disk0. Post the output to your question. This command will not change your Mac. The command just prints out the GUID partition table (GPT). – David Anderson Feb 28 '21 at 02:16
  • It's unbelievable how macOS keeps resetting people's partition type codes like this as if it were malware. I've had to fix this exact issue three times in the last day just from doing APFS resize operations in Mojave's disk utility. – Andreas Feb 28 '21 at 04:04

1 Answers1

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Boot to the Catalina installer and enter the commands shown below.

Note: The values 409640 and 349609376 were taken from the output posted in the question.

gpt -f remove -i 2 disk0
gpt -f add -i 2 -b 409640 -s 349609376 -t apfs disk0

 

David Anderson
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