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After installing Ubuntu as a second system on my Macbook following this tutorial https://www.maketecheasier.com/install-dual-boot-ubuntu-mac/ everything was just working fine and I was able to boot into either macOS or Ubuntu via rEFInd.

Then I resized macOS's partition again to create a partition to share data between macOS and Ubuntu. Unfortunately rEFInd does not find the macOS Partition anymore and I am therefore not able to boot into macOS.

My partitions look like this at the moment:

sda             489,1G                              
├─sda1 vfat       200M /boot/efi                    EFI
├─sda2 apfs       351G                              
├─sda3 swap       3,7G [SWAP]                       
├─sda4 ext4     115,5G /                            
└─sda5 vfat      18,6G                              SHARE

Any help would be highly appreciated.

Edits:

  • I used the builtin Mac Program to resize the partition

  • Output of sudo gdisk -l /dev/sda:

    GPT fdisk (gdisk) version 1.0.5
    
     Partition table scan:
       MBR: hybrid
       BSD: not present
       APM: not present
       GPT: present
    
     Found valid GPT with hybrid MBR; using GPT.
     Disk /dev/sda: 1025610768 sectors, 489.0 GiB
     Model: Crucial_CT525MX3
     Sector size (logical/physical): 512/512 bytes
     Disk identifier (GUID): 2AA86904-096B-4D1C-9DD0-3C8B1FD84B37
     Partition table holds up to 128 entries
     Main partition table begins at sector 2 and ends at sector 33
     First usable sector is 34, last usable sector is 1025610734
     Partitions will be aligned on 8-sector boundaries
     Total free space is 1653 sectors (826.5 KiB)
    
     Number  Start (sector)    End (sector)  Size       Code  Name
        1              40          409639   200.0 MiB   EF00  EFI System Partition
        2          409640       736548223   351.0 GiB   FFFF  tichan
        3       775612416       783423487   3.7 GiB     8200  
        4       783423488      1025609727   115.5 GiB   8300  
        5       736548864       775612415   18.6 GiB    0700 
  • What tool did you use to resize the macOS partition? Also, edit your question and add the output from the command sudo gdisk -l /dev/sda. – David Anderson Aug 6 at 14:46
  • Edited information :) – Uncle Cuppa Aug 7 at 6:48
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The type GUID for partition 2 of /dev/sda is wrong. The commands below will correct the problem. Enter the commands in an Ubuntu terminal window.

sudo gdisk /dev/sda
t
2
AF0A
w
y

Note: I realize the gdisk output shows hybrid partitioning. However, both macOS and Ubuntu should ignore the 2nd, 3rd and 4th entries in the MBR partition table.

| improve this answer | |
  • Just did that, but now running efibootmgr, does not show me MacOS or rEFInd anymore. How am I now able to boot into macOS? – Uncle Cuppa Aug 7 at 10:12
  • The efibootmgr functionality is not very compatible with how a Mac operates. If you want to choose macOS as the default to boot from Ubuntu, I would suggest doing this by modifying the rEFInd configuration instead of using efibootmgr. You can also use the Mac Startup Manager to choose to boot macOS. – David Anderson Aug 7 at 17:52

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