I have a GCE machine, but the other day I tried upgrading Ubuntu (from 18.04 to 20.04), and after rebooting, I couldn't connect via SSH again. I've already rebooted the machine, stopped it, and restarted it. But I can't log in via SSH. When I try from the console, I get: "Connection via Cloud Identity-Aware Proxy Failed. Code: 4003, Reason: failed to connect to backend". I also tried using gcloud compute ssh, but I get: "ERROR: (gcloud.compute.ssh) [/usr/bin/ssh] exited with return code [255]".
Any ideas on what I could try?