GRUB2 boot failure: “Error: Out of disk”

Question

1. Create two or more partitions in one USB disk.
2. Install any Linux system in second or later partition.
3. Install GRUB2 in the disk. Boot directory is the /boot on the partition where Linux system is installed.
4. Attempt to boot in the disk.
5. Error: Out of disk.

(In rescue mode, shell can read the files inside /bin but cannot read the files inside /boot, /usr, etc.)

Why does this happen and what should I do to solve this problem?

Answer 1

Maybe the size of the first partition is too small, so that initrd can not be fit into it. Don't know, just a guess.

Check with an increased partition size.