FiloSottile/age · error

expected unsupported stanza, got %q

Error message

expected unsupported stanza, got %q

What it means

This error is thrown by the plugin's test/protocol helper expectUnsupported when, after sending an unsupported-recipient command, the plugin reads back a stanza whose Type is not "unsupported". It indicates the v1 plugin protocol handshake deviated from the expected sequence: the counterpart responded with a different stanza type than the required "unsupported" acknowledgment.

Source

Thrown at plugin/plugin.go:664

	case "fail":
		if err := expectStanzaWithNoBody(s, 0); err != nil {
			return nil, fmt.Errorf("%v", err)
		}
		return s, nil
	case "ok":
		return s, nil
	default:
		return nil, fmt.Errorf("expected ok or fail stanza, got %q", s.Type)
	}
}

func expectUnsupported(sr *format.StanzaReader) error {
	unsupported, err := sr.ReadStanza()
	if err != nil {
		return fmt.Errorf("failed to read unsupported stanza: %v", err)
	}
	if unsupported.Type != "unsupported" {
		return fmt.Errorf("expected unsupported stanza, got %q", unsupported.Type)
	}
	return expectStanzaWithNoBody(unsupported, 0)
}

func (p *Plugin) writeError(args []string, err error) error {
	s := &format.Stanza{Type: "error", Args: args}
	s.Body = []byte(err.Error())
	if err := s.Marshal(p.stdout); err != nil {
		return fmt.Errorf("failed to write error stanza: %v", err)
	}
	if err := expectOk(p.sr); err != nil {
		return fmt.Errorf("%v", err)
	}
	return nil
}

View on GitHub (pinned to b74dce4cdb)

Solutions

1. Inspect the %q value in the message to see which stanza type was actually received and trace who emitted it.
2. Verify the client/peer implements the age plugin protocol's unsupported-stanza acknowledgment correctly.
3. Confirm the order of stanzas written before calling expectUnsupported matches the protocol spec.
4. If you added custom stanzas, ensure unsupported recipients still produce a Type "unsupported" stanza.

Example fix

// before
s := &format.Stanza{Type: "ack"}
// after
s := &format.Stanza{Type: "unsupported"}

if st, ok := stanza.(*format.Stanza); !ok || st.Type != "unsupported" {
    return fmt.Errorf("peer did not send unsupported stanza, got %v", st)
}

When it happens

Trigger: Calling Plugin.RecipientV1 or Plugin.IdentityV1 in a mode that exercises the unsupported-stanza path while the StanzaReader returns a stanza with a Type other than "unsupported" (e.g. an "ok", "error", or body-carrying stanza).

Common situations: Custom or third-party age plugin clients that emit a wrong acknowledgement stanza; protocol-level regressions after changing the plugin message flow; a peer replying with an error stanza where an unsupported ack was expected.

Related errors

• malformed recipient stanza: unexpected argument count
• malformed recipient stanza: invalid index
• malformed recipient stanza: unexpected index
• repeated labels stanza
• %s

AI-assisted analysis of FiloSottile/age@b74dce4cdb (2026-08-31). Data as JSON: /api/errors/8a7857dfff89937c. Report an issue: GitHub.