plan contains both database group and databases, but only on

Error message

plan contains both database group and databases, but only one is allowed

What it means

A plan spec must select its target databases via exactly one mechanism: a database group, or an explicit list of databases. validateSpecs rejects CreatePlan/UpdatePlan requests that set both a database group resource and explicit database resources in the same plan, because the combined targeting semantics would be ambiguous.

Source

Thrown at backend/api/v1/plan_service.go:678

	}
	// Allow at most one ChangeDatabaseConfig with release.
	if releaseCount > 1 {
		return nil, errors.Errorf("plan contains multiple change database configs with release, but only one is allowed")
	}

	// Allow at most one instance.
	if len(instanceTargets) > 1 {
		return nil, errors.Errorf("plan contains targets on multiple instances, but only one instance is allowed")
	}

	// Allow at most one database group.
	if len(databaseGroups) > 1 {
		return nil, errors.Errorf("plan contains multiple database groups, but only one is allowed")
	}

	// Don't allow mixing database group and databases.
	if len(databaseGroups) > 0 && len(databaseNames) > 0 {
		return nil, errors.Errorf("plan contains both database group and databases, but only one is allowed")
	}

	// Validate resources existence.
	if len(instanceTargets) == 1 {
		instance, err := getInstanceMessage(ctx, s, instanceTargets[0])
		if err != nil {
			return nil, err
		}
		if instance.Deleted {
			return nil, connect.NewError(connect.CodeNotFound, errors.Errorf("instance %q has been deleted", instanceTargets[0]))
		}
	}

	if len(databaseGroups) == 1 {
		name := databaseGroups[0]
		groupProjectID, _, err := common.GetProjectIDDatabaseGroupID(name)
		if err != nil {
			return nil, connect.NewError(connect.CodeInvalidArgument, errors.Errorf("invalid database group name %q", name))

View on GitHub (pinned to 1870550677)

Solutions

Remove the explicit database resources and keep only the database group spec
Remove the database group spec and keep only the explicit database list
If both targets are needed, issue separate plans — one per targeting style

Example fix

// before
plan.specs = [{databaseGroup: "projects/p/databaseGroups/prod"},
              {databases: ["projects/p/databases/db1"]}]
// after
plan.specs = [{databaseGroup: "projects/p/databaseGroups/prod"}]

Defensive patterns

Strategy: validation

Validate before calling

if len(spec.GetDatabaseGroup()) > 0 && len(spec.GetDatabases()) > 0 {
  return fmt.Errorf("spec sets both databaseGroup and databases; pick one")
}

Try / catch

var cerr *connect.Error
if errors.As(err, &cerr) && strings.Contains(cerr.Message(), "both database group and databases") {
  // clear one targeting style and resubmit
}

Prevention

Model targeting mode as an enum in client code so only one field can be set
Clear the databases list whenever a group is selected (and vice versa) in UI code

When it happens

Trigger: Calling CreatePlan or UpdatePlan where plan specs contain both a database_group resource name and database resource names (e.g. projects/{p}/databases/{db}) simultaneously — typically when a client appends a fallback database entry alongside a group, or merges two different spec styles.

Common situations: UI or tooling that pre-fills explicit databases and then adds a group when the user changes selection mode without clearing the other field; migration of older plan payloads that mixed both styles; hand-written API scripts constructing specs incorrectly.

Related errors

AI-assisted analysis of bytebase/bytebase@1870550677 (2026-09-06). Data as JSON: /api/errors/6d49f887fbfdb27d. Report an issue: GitHub.