Comment 118 for bug 1835660

I have successfully resolved the problem. I don't know exactly what helped because I did a few things. Namely: I switched all SATA cables from the second controller to the first (my computer motherboard has two SATA controllers) and disabled the Compatibility Support Module. Unfortunately, CSM turned off the BIOS boot options, only UEFI was left. After changing the settings and rebooting, the message "Initramfs unpacking failed: Decoding failed" was still showing on the screen, but the system continued the boot process and finally saw the Ubuntu Server 20.04 installer