Show 'Invalid header flag bits, must be 0x0 for connack packet' when connect

[ghzjtian]

Test Information

• MQTTJS version: 5.5.3
• Chrome: Version 124.0.6367.80
• Frontend Vue version: 3.2.47
• MQTT broker version: 3.1.1

Issue

When i use mqttjs wss to connect to old broker, it return [ 0x22, 0x02, 0x00, 0x00 ], but the MQTTJS throw error , the message is connection error: Error: Invalid header flag bits, must be 0x0 for connack packet , I know that from 5.0.0, it will check the format of message according to the MQTT Official Document.

I searched online but couldn't find the answer.
I cannot modify this custom MQTT broker either.

So, my question is : how to close the format check logic?

[robertsLando]

So, my question is : how to close the format check logic?

The parsing/encoding of mqtt packets are handeld by mqtt-packet, dunno if there is an option to disable this check there, you should check or maybe @mcollina knows