jackc/pgx · error

unknown startup message code: %d

Error message

unknown startup message code: %d

What it means

Error "unknown startup message code: %d" thrown in jackc/pgx.

Source

Thrown at pgproto3/backend.go:165

		err = b.sslRequest.Decode(buf)
		if err != nil {
			return nil, err
		}
		return &b.sslRequest, nil
	case cancelRequestCode:
		err = b.cancelRequest.Decode(buf)
		if err != nil {
			return nil, err
		}
		return &b.cancelRequest, nil
	case gssEncReqNumber:
		err = b.gssEncRequest.Decode(buf)
		if err != nil {
			return nil, err
		}
		return &b.gssEncRequest, nil
	default:
		return nil, fmt.Errorf("unknown startup message code: %d", code)
	}
}

// Receive receives a message from the frontend. The returned message is only valid until the next call to Receive.
func (b *Backend) Receive() (FrontendMessage, error) {
	if !b.partialMsg {
		header, err := b.cr.Next(5)
		if err != nil {
			return nil, translateEOFtoErrUnexpectedEOF(err)
		}

		b.msgType = header[0]

		msgLength := int(int32(binary.BigEndian.Uint32(header[1:])))
		if msgLength < 4 {
			return nil, fmt.Errorf("invalid message length: %d", msgLength)
		}

View on GitHub (pinned to ec1a0befd2)

When it happens

Trigger: Thrown at pgproto3/backend.go:165 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/393e0fbc500066cf.json. Report an issue: GitHub.