Aias00 opened a new issue, #6839: URL: https://github.com/apache/shenyu/issues/6839
## Description `Connect.allowedProtocolVersion` compares equality to `MqttVersion.MQTT_3_1.protocolLevel()` (level 3) only. Level 4 (MQTT 3.1.1) and level 5 (MQTT 5.0) are refused with `CONNECTION_REFUSED_UNACCEPTABLE_PROTOCOL_VERSION`. MQTT 3.1.1 has been the standard since 2014, so virtually every modern MQTT client (which defaults to 3.1.1) is rejected; the broker is effectively unusable for standard clients. ## Location - `shenyu-protocol/shenyu-protocol-mqtt/src/main/java/org/apache/shenyu/protocol/mqtt/Connect.java:91` ## Impact Virtually all modern MQTT clients rejected at CONNECT; broker only accepts legacy 3.1. ## Suggested fix Accept `MqttVersion.MQTT_3_1_1.protocolLevel()` (and consider 5.0). ## Related existing Distinct from MQTT-01 (#6637, missing `return` after protocol-version rejection). (Secondary: the missing `return` at `Connect:56-57` after rejection is already tracked by MQTT-01.) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
