# MQTT engine: Failed to handle message on topic

**URL:** <https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968>\
**Category:** 3rd Party Modules\
**Created:** [September 3, 2019, 1:09pm UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968 "2019-09-03T13:09:57Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![lorenzo.milesi](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lorenzo.milesi/32/10045_2.png) [@lorenzo.milesi](https://forum.inductiveautomation.com/u/lorenzo.milesi)\
**Post date:** [September 3, 2019, 1:09pm UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968/1 "2019-09-03T13:09:57Z")

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Hi.

I’m investigating some MQTT server disconnection issues from the Engine server and I found the below exception recurring **every single second**. While data is arriving on the server it’s continuously throwing this error.

Ignition server 7.9.12, MQTT Engine and Transmission version 3.4.7.

What could cause it?  
thanks

```auto
INFO | jvm 1 | 2019/09/03 13:04:57 | E [c.c.m.e.g.EngineCallback] [13:04:57]: Failed to handle message on topic spBv1.0/dir01/NDATA/ips-edge-00005
INFO | jvm 1 | 2019/09/03 13:04:57 | java.util.concurrent.RejectedExecutionException: Task com.cirruslink.mqtt.engine.gateway.EngineCallback$$Lambda$863/62337317@308da7eb rejec
ted from java.util.concurrent.ThreadPoolExecutor@53a66e10[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0]
INFO | jvm 1 | 2019/09/03 13:04:57 | at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
INFO | jvm 1 | 2019/09/03 13:04:57 | at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
INFO | jvm 1 | 2019/09/03 13:04:57 | at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
INFO | jvm 1 | 2019/09/03 13:04:57 | at com.cirruslink.mqtt.engine.gateway.EngineCallback.messageArrived(EngineCallback.java:174)
INFO | jvm 1 | 2019/09/03 13:04:57 | at com.cirruslink.chariot.client.CirrusClient.messageArrived(CirrusClient.java:546)
INFO | jvm 1 | 2019/09/03 13:04:57 | at org.eclipse.paho.client.mqttv3.internal.CommsCallback.deliverMessage(CommsCallback.java:477)
INFO | jvm 1 | 2019/09/03 13:04:57 | at org.eclipse.paho.client.mqttv3.internal.CommsCallback.handleMessage(CommsCallback.java:380)
INFO | jvm 1 | 2019/09/03 13:04:57 | at org.eclipse.paho.client.mqttv3.internal.CommsCallback.run(CommsCallback.java:184)
INFO | jvm 1 | 2019/09/03 13:04:57 | at java.lang.Thread.run(Thread.java:748)

```

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<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [September 3, 2019, 1:47pm UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968/2 "2019-09-03T13:47:12Z")

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You might need to ping Cirrus Link’s support channels. Only they would know the details. The execution engine pool size == zero looks suspicious.

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [September 3, 2019, 1:58pm UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968/3 "2019-09-03T13:58:24Z")

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Agree with contacting Cirrus.

Maybe the module was restarted at some point but there’s a bug there?

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<div class="post-metadata">

**Author:** ![lorenzo.milesi](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lorenzo.milesi/32/10045_2.png) [@lorenzo.milesi](https://forum.inductiveautomation.com/u/lorenzo.milesi)\
**Post date:** [September 3, 2019, 2:20pm UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968/4 "2019-09-03T14:20:50Z")

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Thank you both, I will write to CL support!

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<div class="post-metadata">

**Author:** ![lorenzo.milesi](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lorenzo.milesi/32/10045_2.png) [@lorenzo.milesi](https://forum.inductiveautomation.com/u/lorenzo.milesi)\
**Post date:** [September 5, 2019, 7:01am UTC](https://forum.inductiveautomation.com/t/mqtt-engine-failed-to-handle-message-on-topic/27968/5 "2019-09-05T07:01:44Z")

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CL support provided me an updated (test) module which fixes the issue! Just in case anyone else runs into the same issue this should get fixed in 3.4.8.