similar issue here. Just one release step later (0.16 to the new 0.17).
I got currently 0.16 installed on the device (according to GS290 /e/ Systemupdates Menu).
On offer for install (and already downloaded) is 0.17.
When I choose to install, I end up eventually on a recovery screen, where I can choose to
with a terminal output below that says:
Finding update package…
Opening update package…
Verifying update package…
E: failed to verify whole-file signatue
Update package verification took 6.2 s (rersult 1)
E: Signature verification failed
E: error 21
Install completed with status 1.
I guess choosing Apply Update would bring me to the same point again,
but I didn’t dare to and choose Reboot instead.
I created a ticket in the gitlab issue tracker for this problem. You may just add a comment to the ticket that you’ve got the same problem to increase the probability that is topic is getting any attention at all. The gitlab repository needs another account, but it is quickly set up.