# `migration.decision_unknown`

Migration decides about something that is not changing.

Area 5, [Data](../topics/data.md); not declinable; the next step is usually the agent's.

```jadpo
migration {
    Note.stars: {
        backfill: 3
    }
    Note.body: FieldChange.retired
}
```

```text
error: Nothing about `Note.body` needs a decision
 --> database/migrations/20261020T1401_add_stars/changes.jadpo:5:5
  |
5 |     Note.body: FieldChange.retired
  |     ^^^^^^^^^ no such change
  reason: A migration's `changes.jadpo` holds only the decisions its own changes need, and nothing `20261020T1401_add_stars` changes about `Note.body` does: a decision is a value for existing rows of a required field or for rows a field no longer allows, or retiring a field that is gone.
  next: Remove `Note.body` (agent)
  rule: migration.decision_unknown
  help: https://jadpo.dev/docs/errors/migration.decision_unknown

check failed: 1 error, 4 files
```