MacBook Pro 2019 can't boot live USB

I downloaded Ubuntu 18.04.3 LTS and put it on a USB flash drive. Rebooted the MacBook into recovery mode (Command+R) and enabled booting of external media and unsigned operating systems. Rebooted again holding Option and selected to boot from my USB drive ("EFI Boot" in the boot menu).

The Ubuntu boot menu (GNU GRUB version 2.02) shows up, but no matter what I choose in the menu, it just goes into a kernel panic with a lot of ACPI related errors, including this one:

ERROR: Unable to locate IOAPIC for GSI 34

System information:

MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports)

• Processor: 1.4 GHz Quad-Core Intel Core i5
• Memory: 16 GB 2133 MHz LPDDR3
• Graphics: Intel Iris Plus Graphics 645 1536 MB
• macOS Catalina (version 10.15.1)

Solution 1:

I had the same issue and was able to pass that step by adding noapic or acpi=strict (more lax approach to ACPI from kernel) to the GRUB boot loader line:

linux /casper/vmlinuz [...] quiet splash noapic ---

But after this, the boot gets stuck on another kernel panic related to EFI. This you can bypass if you tell the kernel to not start the EFI runtime -strongly not recommended:

linux /casper/vmlinuz [...] quiet splash noapic efi=noruntime ---

But the boot doesn't complete and probably your mac will reboot without finalizing the full boot process.