Comment 3 for bug 1920009

wrote 21.04 build 21 March to USB stick after checking image with gtkhash. Used this LIVE USB to install 21.04 to a second USB stick, sdb. Normal installation until near the end when BOOM
Unable to install grub in dev/sdb (as superuser). Executing 'grub-install /dev/sdb' failed. This is a fatal error. Only these 2 USB drives sda and sdb are present, no other drives.

This time I freshly created with gparted a GPT USB and a smaller ext4 partition for root, a larger ext4 partition for /home, and a small EFI partition flagged as esp,boot. Boot loader marked as sdb. No files anywhere. Since freshly formatted with Gparted, no formatting during installation. sda is the LIVE USB stick. Choice was 'other' installation, not a full erase and install.

This prevents me from test driving 21.04 as a full install.