I have been trying to install (i.e. dual boot) Ubuntu 20.04 LTS on Macbook Pro 2019. I disabled the T2 chip and disabled the security system by >
csrutil disable in recovery mode. I followed the usual steps:
created a boot-able image on a USB flash device (using Etcher). The iso image was obtained from ubuntu.com.
disabled T2 and SIP security system in recovery mode as stated above.
Created 100 GB GUID formatted FAT32 partitions on internal SSD
Held "Option" key as power on the computer
EFI rebooted from USB drive
Clicked on "install Ubuntu", chose "allow third party ...", then "something else".
On the table for manual partitioning, chose the partition on which Ubuntu was supposed to be installed, "Ext4journaling file system", "format the partition", mount point "/". Clicked on "continue".
Got the message:
the attempt to mount a file system with type vfat in/dev/nvme0n1p1 at /boot/efi failed
Clicked on continue. Then a screen with message
Creating ext4 filesystem for / in partition #3 of /dev/nvme0n1...
The installation got stuck in this stage for hours until I turned off the computer.
I even tried running Ubuntu from live USB drive, using GParted tool to partition the drives. The results was the same.
I also tried installing Ubuntu on an external sda drive with its own EFI partition. The result was the same. I still got the message "the attempt to mount a file system with type vfat in/dev/nvme0n1p1 at /boot/efi failed" and froze on "Creating ext4 filesystem for / in partition #3 of /dev/nvme0n1..." the same as above.
BTW, I also tried installing rEFI boot manager with no success. I have basically followed the instructions in https://linuxnewbieguide.org/how-to-install-linux-on-a-macintosh-computer/#refind and some other places without much success.
I tried dual booting with two different MAC OS, Catalina and Big Sur. The results were the same. Reinstalled Mac OS a couple of times to ensure, file corruption is not causing this. Always obtained the same results.