nats-io/nats-server · error

no matching transforms available

Error message

no matching transforms available

What it means

Subject-transform application: none of the configured transforms matched the subject being remapped (the match loop fell through), so ErrNoTransforms is returned instead of a transformed subject. The subject and the account's transform list are the mismatched inputs.

Source

Thrown at server/errors.go:210

	ErrClusterNameConfigConflict = errors.New("cluster name conflicts between cluster and gateway definitions")

	// ErrClusterNameRemoteConflict signals that a remote server has a different cluster name.
	ErrClusterNameRemoteConflict = errors.New("cluster name from remote server conflicts")

	// ErrClusterNameHasSpaces signals that the cluster name contains spaces, which is not allowed.
	ErrClusterNameHasSpaces = errors.New("cluster name cannot contain spaces")

	// ErrClusterNameReserved signals that the cluster name is reserved for internal protocol use.
	ErrClusterNameReserved = errors.New("cluster name is reserved")

	// ErrMalformedSubject is returned when a subscription is made with a subject that does not conform to subject rules.
	ErrMalformedSubject = errors.New("malformed subject")

	// ErrSubscribePermissionViolation is returned when processing of a subscription fails due to permissions.
	ErrSubscribePermissionViolation = errors.New("subscribe permission violation")

	// ErrNoTransforms signals no subject transforms are available to map this subject.
	ErrNoTransforms = errors.New("no matching transforms available")

	// ErrCertNotPinned is returned when pinned certs are set and the certificate is not in it
	ErrCertNotPinned = errors.New("certificate not pinned")

	// ErrDuplicateServerName is returned when processing a server remote connection and
	// the server reports that this server name is already used in the cluster.
	ErrDuplicateServerName = errors.New("duplicate server name")

	// ErrMinimumVersionRequired is returned when a connection is not at the minimum version required.
	ErrMinimumVersionRequired = errors.New("minimum version required")
	// ErrLeafNodeMinVersionRejected is the leafnode protocol error prefix used
	// when rejecting a remote due to leafnodes.min_version.
	ErrLeafNodeMinVersionRejected = errors.New("connection rejected since minimum version required is")

	// ErrInvalidMappingDestination is used for all subject mapping destination errors
	ErrInvalidMappingDestination = errors.New("invalid mapping destination")

	// ErrInvalidMappingDestinationSubject is used to error on a bad transform destination mapping

View on GitHub (pinned to 3a66a489d2)

Solutions

  1. Add a transform rule (or broader wildcard) that matches the subject
  2. Verify the transform source pattern and subject spelling
  3. Handle ErrNoTransforms as pass-through if that is the intended semantics
Defensive patterns

Strategy: fallback

When it happens

Trigger: Thrown at server/errors.go:210 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nats-io/nats-server@3a66a489d2 (2026-09-02). Data as JSON: /api/errors/25b32cab3057b477. Report an issue: GitHub.