Rpi4 Ubuntu is not booting up

[get4gopim]

I have RPI4 - 4GB and 8GB variants. In 4GB variant I tried the below options and everything is working fine.

• Installed "Raspberry Pi OS" via micro sd card
  Installed "Raspberry Pi OS" via SSD and booting from SSD
  Installed "Ubuntu 18.x" via micro sd card (both 32 and 64 bits)
  Installed "Ubuntu 20.4" via micro sd card

in order to boot via SSD i have changed the bootloader to beta and installed pi-eeprom update. No issues in this setup.

I tried the same in 8GB variant which I received recently. The Raspberry Pi OS is successfully boot from micro sd and SSD without any problem.
I also tried "Manjaro 64 bit OS" via micro SD card, it is also working fine.

When I tried to install "Ubuntu 20.x or 18.x" (both 32 and 64 bits) via micro sd card, it is not booting and it keep saying "start4.elf is not compatible". (see the attached images below url).
The same image burned on the micro sd card is able to boot from my other RPI4 device.

Boot Startup Error:
https://ibb.co/Yh7ZmLh

Boot Loader Version:
https://ibb.co/ygGd9fM

[trejan]

When I tried to install "Ubuntu 20.x or 18.x" (both 32 and 64 bits) via micro sd card, it is not booting and it keep saying "start4.elf is not compatible". (see the attached images below url).

The Pi 4 8GB needs a newer firmware + kernel than what is in the pre-built Pi image on their website. You need to wait for Ubuntu to update the image. You can try fully updating the card in another Pi before trying it in the Pi 4 8GB but I've no idea if Ubuntu have included the necessary kernel change yet.

[geev03]

Placed the sd card from rPi-4 into rPi4-8, and there was no problem with the boot up. The probe details are at
https://linux-hardware.org/?probe=202f337a74

[perlsite]

I still boot Ubunutu 20.04 via sdcard. Is it possible to boot now without sdcard in Ubuntu? I know that it is possible with Raspberry Pi OS.