Solved -- QoS=0 and retain messages don't seem to combine well

#1

I have found that sending messages with default QoS=0, although with the ‘retain’ flag activated (with either MuQTTHub web or Mosquitto), does not retain them: a later subscription to the topic does not receive the message.
However, if I use QoS = 1 and ‘retain’ flag, messages are retained.
Although, also, there is a limitation: I must subscribe to the exact topic to receive retained messages. Wilcards + or # are not ‘understood’ and retained messages are not received if they are used.
Is there something I can do? Switching to Q0S = 1 is not always feasible, as I am using third party software where I cannot change it easily. And also, the second problem (not possible to use wildcards for those retained messages) does not allow me to use LWT messages to, for example, detect ‘alive’ devices.
Thanks a lot

#2

Hello.

Thanks for reporting. Just confirm problem reported as you describe. We should upload an update fixing QoS=0 retained messages plus retained message reception when wildcard subscription is received (which also affects LWT).

We will keep you updated.

#3

Hello.

We have pushed a platform update that also solves this issue with retain activation when QoS=0 but also retain message reception on subscribe when using wildcards. It should also fix LWT problem you described.

Please, let us know if it works for you.
Best Regards

#4

It works very well. Thank for the solution and for the quick response time!