jackc/pgx · error

unknown message type: %c

Error message

unknown message type: %c

What it means

Error "unknown message type: %c" thrown in jackc/pgx.

Source

Thrown at pgproto3/backend.go:236

			msg = &SASLResponse{}
		case AuthTypeSASLFinal:
			msg = &SASLResponse{}
		case AuthTypeGSS, AuthTypeGSSCont:
			msg = &GSSResponse{}
		case AuthTypeCleartextPassword, AuthTypeMD5Password:
			fallthrough
		default:
			// to maintain backwards compatibility
			msg = &PasswordMessage{}
		}
	case 'Q':
		msg = &b.query
	case 'S':
		msg = &b.sync
	case 'X':
		msg = &b.terminate
	default:
		return nil, fmt.Errorf("unknown message type: %c", b.msgType)
	}

	msgBody, err := b.cr.Next(b.bodyLen)
	if err != nil {
		return nil, translateEOFtoErrUnexpectedEOF(err)
	}

	b.partialMsg = false

	err = msg.Decode(msgBody)
	if err != nil {
		return nil, err
	}

	if b.tracer != nil {
		b.tracer.traceMessage('F', int32(5+len(msgBody)), msg)
	}

View on GitHub (pinned to ec1a0befd2)

When it happens

Trigger: Thrown at pgproto3/backend.go:236 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /data/errors/6326f2f5dc87fa7b.json. Report an issue: GitHub.