AWS IoT has a message size limit of 128KB and will disconnect the client if it receives a message that exceeds this limit.

As a result, messages published from MQTT Transmission or MQTT Engine that exceed the limit can cause connection to the broker to oscillate.

The two likely causes of large messages are:

  • MQTT Sparkplug BIRTH and DEATH message lengths
  • Slow tag pacing  


Review the How can I reduce the message size published by MQTT Transmission tutorial for steps to reduce the published message size.


Unable to Resolve?

If the troubleshooting tips did not help you resolve your issues, please open a ticket with Support making sure to include the MQTT Engine or MQTT Transmission logs as appropriate.  

From the Ignition Logs view, select the Download icon to download a copy of the system-name.idb file to your local file system. You will need to compress (zip, 7z or rar) this file before sending to Support.



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