With the proper updated boot loader a Raspbery Pi 4 model B can boot from an SSD drive connected to the USB3 port typically with an SATA - USB converter. This is well known and works well with both Raspbian OS and Ubuntu, e.g Ubuntu 64 bit Server for Raspberry Pi and I have that working on more than one Raspberrpy Pi 4 Model B with e.g. 2 or 4 Gb RAM.
However I cannot boot from an SSD with the NextCloud Home Ubuntu appliance image. I'm guessing this has to to with the fact that this appliance is based on the Ubuntu core 18, published on 2020-06-16.
Do anybody know of a workaround or do anybody know if this this image is going to be updated?
[Edit: I've now tried booting the "raw", i.e. not the appliance image, Ubuntu core 20 and even the Core 22 (dangerous edge) from the SSD and it will not boot. However the very same SSD drive connected to the very same Raspberry Pi boots with no problems on Ubuntu 21.04 Server (ubuntu-21.04-preinstalled-server-arm64+raspi.img.xz).
This leads me to the conclusion that this is a feature built into Ubuntu Core and not specific for the NextCloud Home Ubuntu appliance image per se.
So maybe the question should be rephrased as Why cannot Ubuntu Core boot from an SSD on a Raspberry 4 when Ubuntu can? -- and is there a work-around? ]
