Great question. In Prefect 3.x,

version: null

in a deployment just means you haven’t provided a version string for that deployment. It’s optional metadata and has no impact on scheduling, triggering, or worker execution. Key points: - What it is: A human-readable label for the deployment (e.g., a git SHA, tag, or “v1.2.3”) to help you track what code/config was deployed and to browse/rollback in version history. - When it’s null: You didn’t set it. Prefect may infer one at deploy time: - If you’re in a Git context, Prefect will typically use the first 8 chars of the current commit SHA. - Otherwise it may fall back to your flow’s version (from

@flow(version="...")

) or a file hash. - What it’s not: It does not affect runs, schedules, or workers. It’s purely informational. - Related fields:

version_type

and

version_info

can capture structured details (e.g., VCS provider, commit, branch). You can leave them alone unless you want to control how version info is detected. How to set it explicitly: - Via Python

from prefect import flow

@flow
def my_flow():
    ...

my_flow.from_source("<https://github.com/org/repo>", "flows/my.py:my_flow").deploy(
    name="prod",
    version="2025.11.07",  # any string you like
)

- Or set a flow version that Prefect can use as a fallback:

@flow(version="v1.2.3")
def my_flow():
    ...

Docs: - Deployments overview - Deployment versioning guide If you’d like, tell me how you’re creating deployments (CLI or Python) and whether you want to use git tags/SHAs or a custom scheme—I can show the exact steps.