Livebook app is suspended after upgraded to v2 machine

[reflow]

I made a livebook app via Deploy Livebook on Fly.io · Fly Docs.
And dashboard recommended me to upgrade it to v2 machine.
So I click the button and run upgrade in web CLI.

After that, the app is suspended.

Below are the logs.

2023-05-29T07:11:51.094 app[b5ea164e] nrt [info] Starting clean up.

2023-05-29T07:11:51.094 app[b5ea164e] nrt [info] Umounting /dev/vdc from /data

2023-05-29T07:11:51.095 app[b5ea164e] nrt [info] error umounting /data: EBUSY: Device or resource busy, retrying in a bit

2023-05-29T07:12:04.778 runner[6e8201ea754387] nrt [info] Pulling container image ghcr.io/livebook-dev/livebook:0.9.1

2023-05-29T07:12:10.716 runner[6e8201ea754387] nrt [info] Successfully prepared image ghcr.io/livebook-dev/livebook:0.9.1 (5.937305804s)

could not find a good candidate within 90 attempts at load balancing. last error: no known healthy instances found for route tcp/443. (hint: is your app shutdown? is there an ongoing deployment with a volume or using the 'immediate' strategy? has your app's instances all reached their hard limit?)

I tried to restart app with fly apps restart -a <my_app>, it returns error.

Error: failed restarting app: Existing lock expires at 2023-05-29T08:11:25.648Z

How can I fix my app?

[allison]

Your app seems to be in a “detached” state - this is a sort of halfway-migrated state that should only happen while an app is being migrated.

Fixing this shouldn’t be that bad. You should be able to run

fly resume <appname> # to get out of the "suspended" state
fly scale count 0 -a <appname> # to kill any leftover VMs from the old platform, if there are any
# scale count 0 might take a minute to propagate in the backend.
# if the next command fails, try it again after a few seconds.
fly apps set-platform-version machines -a <appname>

This should get your app in a normal state.