dgraph-io/dgraph · error

error deleting old predicate %s

Error message

error deleting old predicate %s

What it means

dropDeprecated iterates over deprecatedPreds and issues an ATTR drop operation through alterWithClient. When the Dgraph alter call fails for a given predicate, the error is wrapped as 'error deleting old predicate %s'. It means the schema migration could not remove a deprecated predicate from the v21.03 schema.

Source

Thrown at upgrade/change_v21.03.0.go:129

	"dgraph.graphql.p_sha256hash":      {},
}

var deprecatedTypes = map[string]struct{}{
	"dgraph.type.cors":       {},
	"dgraph.graphql.history": {},
}

func dropDeprecated(dg *dgo.Dgraph) error {
	if !Upgrade.Conf.GetBool(deleteOld) {
		return nil
	}
	for pred := range deprecatedPreds {
		op := &api.Operation{
			DropOp:    api.Operation_ATTR,
			DropValue: pred,
		}
		if err := alterWithClient(dg, op); err != nil {
			return errors.Wrapf(err, "error deleting old predicate %s", pred)
		}
	}
	for typ := range deprecatedTypes {
		op := &api.Operation{
			DropOp:    api.Operation_TYPE,
			DropValue: typ,
		}
		if err := alterWithClient(dg, op); err != nil {
			return errors.Wrapf(err, "error deleting old type %s", typ)
		}
	}
	fmt.Println("Successfully dropped the deprecated predicates")
	return nil
}

func upgradePersitentQuery() error {
	dg, cb := x.GetDgraphClient(Upgrade.Conf, hasAclCreds())
	defer cb()

View on GitHub (pinned to 759e242be6)

Solutions

1. Verify the Alpha address/credentials passed to the upgrade command are correct and reachable.
2. Re-run the upgrade with admin ACL credentials (or --acl credentials) so alter operations are permitted.
3. Check Alpha logs for the underlying alter failure and fix the root cause (e.g. read-only mode, disk full).
4. Manually drop the predicate via /alter once the cluster is healthy and re-run upgrade.

Example fix

// before
if err := alterWithClient(dg, op); err != nil {
	return errors.Wrapf(err, "error deleting old predicate %s", pred)
}
// after
if err := alterWithClient(dg, op); err != nil {
	return errors.Wrapf(err, "error deleting old predicate %s (check ACL creds and Alpha connectivity)", pred)
}

curl -s http://localhost:8080/alter -XPOST -d '{"drop_attr": "old.pred"}'  # verify alter works and creds are valid before upgrade

if err := upgradeCORS(); err != nil {
	if strings.Contains(err.Error(), "error deleting old predicate") {
		// inspect wrapped cause: retry with admin ACL creds or drop predicate manually
	}
	return err
}

When it happens

Trigger: alterWithClient returns an error when dropping one of the predicates in deprecatedPreds — e.g. the Dgraph Alpha alter endpoint is unreachable, ACL forbids the operation, or the drop op is rejected server-side.

Common situations: Running the upgrade tool against a cluster where the user lacks alter permissions (ACL enabled without admin creds), Alpha address misconfigured in upgrade flags, or a network partition during schema migration.

Related errors

• error deleting old type %s
• error querying old ACL rules: %w
• unable to parse ACLs: %v
• unable to unmarshal ACL: %v :: %w
• error upgrading ACL rules: %w

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/bfd32a72df077a3e. Report an issue: GitHub.