I had this issue crop up today using Z2MQTT 1.36.0-1 and the latest version of HA.
@radionerd solution worked. Puzzling has been working forever then suddenly this!
Hello! The following helped me: using a file editor, I edited the configuration.yaml file in the letter /homeassistant/zigbee2mqtt and rolled back the latest changes. For example, I removed the retention: line, which requires version 5 of the mqtt broker. You can also manually roll back the latest changes. After that, I saved the file and restarted the add-on.
2 years later this still worked! Thanks! For some reason the config tab in the add-on menu does not work properly so this is the best way to solve it.
Somehow I got the error, looks like after HA OS update. But used to work, now it didn’t… so defqon 1 in house with lights just before going to bed. Grrr
Log told me it had to do with the retetion function thus need of version 5…
Thanks to earlier posts started looking in the zigbee2mqtt configiration.yaml and noticed a retention configuration of an old (Tuya power clamp), made a comment of this line and tried to start zigbee2mqtt add on… and it works again! Yeah
Thanks all for pointing direction