Situation: trying to install on USB drive on UEFI system using automated install.
The installation fails saying that it could not find an ESP partition on the installation drive. An ESP partition is present on the hard drive of the system, though.
/dev/sda (hard drive of the system, not for install)
/dev/sdb (hard drive)
/dev/sdc (target USB drive for installation, ESP needs to be created)
/dev/sdd (USB drive on which solus budgie booted (April boot image))