Upgrade is currently blocked because of [robotframework-mqttlibrary](https://github.com/randomsync/robotframework-mqttlibrary), which has not been updated in a while and does not work with paho_mqtt 2.x. The migration is quite simple and described here: https://eclipse.dev/paho/files/paho.mqtt.python/html/migrations.html I have made the necessary changes in robotframework-mqttlibrary (see attached file) and it works with paho_mqtt 2.1 (and API callback version 2). The maintainer of the library does not seem to be active on the project, so we may end up forking it.[MQTTKeywords.py](/uploads/0b00b11a1a6232bafef7793617e25684/MQTTKeywords.py)