Getting StringPayloadHandler error "Invalid tag at Path" on subsequent tag publish

Ignition Maker (8.1.27), MQTT Distributor/Engine/Transmission (4.0.16)

Publishing to a topic for the first time creates the tag as expected, but publishing to it again gets the log message “Invalid tag at path ‘’ - unable to handle payload on custom namespace topic=”. Value changes on the subsequent publish are reflected in the MQTT broker, but not the Ignition tag.

Logger: Error - StringPayloadHandler (com.cirruslink.mqtt.engine.gateway.string.StringPayloadHandler)

This looks to be a known issue related to non JSON payloads that we have a fix for in our nightly build available here

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Confirmed, updating MQTT Engine to the nightly build (4.0.17-SNAPSHOT (b2023050816)) resolves the issue. Thanks!

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I’m having the same issue with my full version gateway. I have upgraded to 4.0.17-SNAPSHOT (b2023051601) but now the tags are not even created on initial MQTT post. I’ve installed the distributor and transaction snapshots and restarted all MQTT modules. Am I missing something?

I note that you have installed MQTT Distributor and MQTT Transmission - you will also need MQTT Engine installed.
If you have Engine installed and configured with a valid custom namespace and are still running into this issue please open a ticket with and include a download of your Ignition logs, an image of your custom namespace configuration and published message topic/payload.

Thanks… I had in fact also installed the Engine and had restarted it as well. I deleted the custom namespace and re-created it and now I’m back up and running. Thanks for the reply.

Glad the issue is resolved