Macbook Air Can Not Start After Trying to Remove Ubuntu

Question

I was trying to remove Ubuntu (dual boot) from my 2017 Macbook Air. Now my computer can not start successfully in either macOS or Linux. When I restart it, it now opens refind, then gnu rnu in both macOS and Linux.

I used Disk Utility when trying to remove Ubuntu. I don't completely remember what I did. However, I could not remove the partition Ubuntu uses. Then, I opened macOS in recovery mode and did some changes using diskutil. The disk now looks like this:

Can you help me fix this without losing my data? Is my data gone for good?

gpt -r show /dev/disk0 shows:

Disk utility shows:

Edit: Output of :

export LC_CTYPE="ASCII"
diskutil unmountdisk disk0
dd if=/dev/disk0 count=1 bs=16 skip=13108482 | vis -cw;echo

Edit: It says resource busy when I entered the command gpt add -i 2 -b 409640 -t apfs disk0.

Answer 1

Note: This answer uses export LC_CTYPE="ASCII". While using export LC_CTYPE="ASCII" works, internally the vis command does not recognize ASCII and defaults to C. So, in the future, export LC_CTYPE="C" (or just export LC_CTYPE=C) should be used instead.

Use the following steps.

1. Boot to the same Recovery Mode used in your question.

2. Enter the following commands. None of these commands alter your Mac. The commands just product diagnostic information, which may be helpful.

   sw_vers
   export LC_CTYPE="ASCII"
   diskutil unmountdisk disk0
   dd if=/dev/disk0 count=1 bs=16 skip=13108482 | vis -cw;echo
   

   Post the output from the above commands to your question.

3. Enter the commands given below.

   diskutil unmountdisk disk0
   gpt -f add -i 2 -b 409640 -t apfs disk0
   diskutil list internal
   

   If the above commands execute successfully, then the name of the APFS volume containing macOS will appear in the output from the command diskutil list internal. If not, then post the output from the above commands to your question, post a comment to my answer and wait for my response. Otherwise, proceed.

4. Enter the following commands. When entering the commands, use the output from the previously entered diskutil list internal command to replace diskXsV with the identifier for the APFS Volume containing macOS and replace diskYsC with the identifier for the Apple_APFS Container listed as the Physical Store for the APFS Volume.

   diskutil info diskXsV | grep "Disk Size"
   diskutil info diskYsC | grep "Disk Size"
   

   If the output from both commands match, then you are done. Otherwise, proceed.

5. Enter the following commands. When entering the commands, use the output from the previously entered diskutil info diskXsV | grep "Disk Size" command to replace SizeInBlocks with the disk size in 512-Byte-Units for the APFS Volume containing macOS.

   diskutil unmountdisk disk0
   gpt -f remove -i 2 disk0
   diskutil unmountdisk disk0
   gpt -f add -i 2 -b 409640 -s SizeInBlocks -t apfs disk0
   

Use of the gpt add Command

This section can be ignored by the OP (user Gizem Kaya) . This section was added to this answer mainly to address concerns posted by user Jean_JD. The add command for gpt includes the -i, -b, -s and -t command-specific options. The table below explains how the default values are determined when one or more of these options is omitted.

Option	Default If Omitted
-i	The first partition in the table with a partition type of zero
-b	The starting sector number of the first available block of an unused disk space.
-s	The largest available size in sectors based on the starting sector number.
-t	A partition type UUID value of 48465300-0000-11AA-AA11-00306543ECAC, which is the same as the hfs alias.

If the case of this answer, the command-specific option -s was omitted from gpt -f add -i 2 -b 409640 -t apfs disk0 command in step 3. When the OP enters the command, the default value of 384370648 will be used for the size in sectors.

Answer 2

First, boot in internet recovery mode (cmd+alt+r at boot) Then verify if the internal disk is always disk0

diskutil list internal

will help you. Then from the terminal verify if it's necessary to remove the entry 2 if present with command (keep in mind replacing diskX with the good value).

gpt -r show diskX

If yes

diskutil unmountdisk diskX
gpt remove -i 2 diskX

Then in all case create this entry:

diskutil unmountdisk diskX
gpt add -i 2 -b 409640 -s  384370648 -t apfs diskX

Then you verify with :

diskutil list internal