# Dataset Reference Tag Not Receiving in MQTT Engine

**URL:** <https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571>\
**Category:** MQTT Modules\
**Created:** [May 9, 2024, 10:33pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571 "2024-05-09T22:33:06Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![timschultzoc](https://avatars.discourse-cdn.com/v4/letter/t/a9adbd/32.png) [@timschultzoc](https://forum.cirrus-link.com/u/timschultzoc)\
**Post date:** [May 9, 2024, 10:33pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571/1 "2024-05-09T22:33:07Z")

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I have Ignition Reference dataset tags that are sending data via MQTT Transmission to Mosquitto, to which MQTT Engine is subscribed. Generally this is working well. However, in some cases I’m receiving this error on the Engine side:

```auto
java.lang.NullPointerException: Cannot invoke "Object.getClass()" because "value" is null
at com.cirruslink.mqtt.common.util.SparkplugUtils.convertToIgnitionDataset(SparkplugUtils.java:720)
at com.cirruslink.mqtt.engine.gateway.sparkplug.SparkplugBPayloadHandler.getIgnitionValue(SparkplugBPayloadHandler.java:1712)
at com.cirruslink.mqtt.engine.gateway.sparkplug.SparkplugBPayloadHandler.handleNodeBirth(SparkplugBPayloadHandler.java:412)
at com.cirruslink.mqtt.engine.gateway.sparkplug.SparkplugPayloadHandler.handlePayload(SparkplugPayloadHandler.java:171)
at com.cirruslink.mqtt.engine.gateway.EngineCallback.lambda$messageArrived$1(EngineCallback.java:247)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)

```

The payload seems fine in MQTT FX, and the payload processes properly as JSON. Any suggestions as to where I can troubleshoot? I unfortunately cannot post the contents of the file.

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**Author:** ![wes.johnson](https://avatars.discourse-cdn.com/v4/letter/w/f14d63/32.png) [@wes.johnson](https://forum.cirrus-link.com/u/wes.johnson)\
**Post date:** [May 10, 2024, 4:21pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571/2 "2024-05-10T16:21:57Z")

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I believe this was a known issue that was fixed in the currently nightly build. Can you upgrade and see if it resolves your issue?

Latest nightly Engine is here: [Nightly Module Builds - MQTT Modules for Ignition 8.x - Confluence](https://docs.chariot.io/display/CLD80/Nightly+Module+Builds)  
Version compatibility is here: [Ignition Compatibility with Cirrus Link Modules - MQTT Modules for Ignition 8.x - Confluence](https://docs.chariot.io/display/CLD80/Ignition+Compatibility+with+Cirrus+Link+Modules)

The current nightly builds are supported on Ignition back to 8.1.2.

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**Author:** ![wes.johnson](https://avatars.discourse-cdn.com/v4/letter/w/f14d63/32.png) [@wes.johnson](https://forum.cirrus-link.com/u/wes.johnson)\
**Post date:** [May 10, 2024, 4:23pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571/3 "2024-05-10T16:23:24Z")

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Also - if you are running in production and want to wait until the official release is available, that should be released before the end of this month. It might be worth sanity testing the nightly in a development environment just to make sure it will work properly once the official release is ready too.

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**Author:** ![timschultzoc](https://avatars.discourse-cdn.com/v4/letter/t/a9adbd/32.png) [@timschultzoc](https://forum.cirrus-link.com/u/timschultzoc)\
**Post date:** [May 10, 2024, 5:48pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571/4 "2024-05-10T17:48:16Z")

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Thanks Wes - I will give this a try, we are on a dev system for the moment. I may drop it into a limited production capacity provided the sanity testing goes well, as I have a pretty tight timeline for this project.

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<div class="post-metadata">

**Author:** ![timschultzoc](https://avatars.discourse-cdn.com/v4/letter/t/a9adbd/32.png) [@timschultzoc](https://forum.cirrus-link.com/u/timschultzoc)\
**Post date:** [May 10, 2024, 8:00pm UTC](https://forum.cirrus-link.com/t/dataset-reference-tag-not-receiving-in-mqtt-engine/571/5 "2024-05-10T20:00:43Z")

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This did resolve the issue - thanks! I’ll let it bake over the weekend in dev and report back any findings.