MQTT 1.x items stop working after enableing MQTT 2.4

I have had a working version of about 4 different nodes running on OH2 via MQTT 1.x (legacy). I then enabled MQTT 2.4 in order to play with some new nodes and learn how to upgrade my .items and .things; however, my old items quit working.

Am I correct to assume that one cannot run both MQTT legacy and 2.4 in tandem? This appears to be so in my case.

How do I bring MQTT legacy back online. I’ve tried uninstalling 2.4, uninstalling/reinstalling legacy, and power cycling with no results.

Thank you for your time.

I would try cleaning the cache then reinstall the binding.

sudo systemctl stop openhab

sudo openhab-cli clean-cache

sudo reboot

Power cycling is never a good idea. It’s always best to stop OH first then reboot when possible.:wink: If your running OH on something like an RPI and using the SD card a power cycle can/will corrupt the card.

No, it should work

Do you have different Client-ids for both Bindings? Mosquitto only allows one connection per clientid.

Is there a solution to this?

My MQTT items stopped working with 2.4 and I don’t have time yet to migrate to the new binding.

Is there a way to get the old ones working again meanwhile?

Enable legacy bindings, uninstall the new MQTT, install mqtt1. Done.


There’s a couple of us that have a small discussion group that share our experience with OH and MQTT. Feel free to look into that guidance here