GCP VM not available via SSH - ERROR: (gcloud.compute.ssh) [/usr/bin/ssh] exited with return code [255]

Getting this error after upgrading a VM:

$ gcloud compute ssh myvm -- -vvv
OpenSSH_***, LibreSSL *.*.*
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: /etc/ssh/ssh_config line 56: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to *.*.*.* [*.*.*.*] port *.
debug1: connect to address *.*.*.* port *: Connection refused
ssh: connect to host *.*.*.* port *: Connection refused
ERROR: (gcloud.compute.ssh) [/usr/bin/ssh] exited with return code [255].

Went ahead and activated the serial port access:

gcloud compute instances add-metadata myvm \
    --metadata=serial-port-enable=1

Accessed it from Google Cloud Console "Remote Access / Connect to Serial Console". Without doing anything else I was able to connect to the VM. I should assume that "Connect to Serial Console" restarts ssh.