My installation failed too.
(i have Android 9 installed)

enabled developer mode enabled USB debugging connected to PC rebooted to FASTBOOT screen started UBports (in Ubuntu linux)

And this error message occured:

Error: fastboot:format: Error: formatting failed: Error: {"error":{"code":1,"cmd":"fastboot format system"},"stderr":"FAILED (Status read failed (No such device))\nfastboot: error: Command failed"}

What happened here?