extended_connack_codes - mqtt/mqtt.org GitHub Wiki

The current CONNACK codes are:

• 0 0x00 Connection Accepted

• 1 0x01 Connection Refused: unacceptable protocol version

• 2 0x02 Connection Refused: identifier rejected

• 3 0x03 Connection Refused: server unavailable

• 4 0x04 Connection Refused: bad user name or password

• 5 0x05 Connection Refused: not authorized

Suggested CONNACK codes:

• Connection Refused: invalid will topic