Deployments unpaused on prefect.serve

[gsakkis]

I have a set of deployments that I pause with prefect deployment schedule pause --all. However after (re)running prefect.serve(*deployments) they are automatically unpaused. Is this expected behavior and if so can it be disabled?

[devin-ai-integration[bot]]

Hi @gsakkis — yes, this is expected behavior currently.

When serve() starts, it calls apply() on each deployment, which sends the schedule definitions from your code to the server. The server then deletes and recreates all schedules from the payload. Since DeploymentScheduleCreate defaults active=True, any previously paused schedules get recreated as active.

Workarounds:

1. Pass active=False in code — schedule helpers support this today:

   from prefect.schedules import Cron
   
   deploy = my_flow.to_deployment(
       "my-deployment",
       schedules=[Cron("0 0 * * *", active=False)]
   )
   serve(deploy)

   Downside: this is static — schedules always start paused regardless of server state.

2. Manage schedules entirely via CLI — if you omit schedule args from to_deployment and instead add schedules through prefect deployment schedule create, then serve restarts won't touch your schedules at all (the update path skips schedules when none are defined in code). This lets you manage active/paused state purely through the CLI.

The gap: there's currently no way to define schedules in code and have serve respect the server-side active state on restart. The update path always replaces schedules wholesale when any are defined in code.

[zzstoatzz]

note that this is related to #15332

and is generally on our radar

[gsakkis]

Thanks, subscribed 👍

Btw the second workaround above doesn't work, at least when I create a schedule from the UI instead of the CLI: when i comment out the cron parameters from to_deployment, the manually created schedule is removed. IOW serve restarts won't touch your schedules at all is not true.