# MQTT Engine INTERNAL\_ERROR crashes Ignition Project
**URL:** https://forum.cirrus-link.com/t/mqtt-engine-internal-error-crashes-ignition-project/446
**Category:** MQTT Modules
**Tags:** mqtt-engine
**Created:** [October 20, 2023, 8:03pm UTC](https://forum.cirrus-link.com/t/mqtt-engine-internal-error-crashes-ignition-project/446 "2023-10-20T20:03:17Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@christiankyte-bright](https://forum.cirrus-link.com/u/christiankyte-bright)
#### Post date: [October 20, 2023, 8:03pm UTC](https://forum.cirrus-link.com/t/mqtt-engine-internal-error-crashes-ignition-project/446/1 "2023-10-20T20:03:17Z")
MQTT Engine 4.0.14
Ignition Version 8.1.23
## Problem Statement
Ignition SFCs are being aborted due to an exception from the MQTT Engine plugin, this happens when the MQTT (RMQ) broker suddenly crashes (hosted on a separate server). The simple answer is to ensure the RMQ Broker doesn’t crash, but I would like a solution that doesn’t include our broker in the dependency chain for Ignition. How can I trap the following errors to prevent Ignition Projects from crashing entirely?
**Screen shot of Ignition Log showing the order of events**
## Code to send MQTT Messages
```python
def _publishEvent(topic, payload):
try:
#Server (see config webui), topic, payload, qos, retain
system.cirruslink.engine.publish("ELK", topic, str(payload).encode(encoding="UTF-8"), 0, 0)
print("publish MQTT for event: {}".format(payload))
except Exception, e:
msg = "Exception thrown publishing MQTT Msg. Topic [{}], Payload [{}]".format(topic, payload)
print(msg)
logger.error(msg)
logger.error(str(e))
```
_ **Note: no log messages are collected with that exception, which tells me the following exceptions are happening in a different call stack. Presumably whatever thread is handing MQTT message sending** _
## MQTT Engine Plugin seems to be crashing with the following stacktrace
```java
EngineCallback - Connection lost due to - Connection Lost
org.eclipse.paho.client.mqttv3.MqttException: Connection lost
at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:197)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.io.EOFException: null
at java.base/java.io.DataInputStream.readByte(Unknown Source)
at org.eclipse.paho.client.mqttv3.internal.wire.MqttInputStream.readMqttWireMessage(MqttInputStream.java:92)
at org.eclipse.paho.client.mqttv3.internal.CommsReceiver.run(CommsReceiver.java:137)
... 1 common frames omitted
```
**Which then causes an exception on each of the running SFC instances, with the following stacktrace… from what I see the meaningful part is:**
```auto
Chart Instance Aborted
Caused by: org.eclipse.tahu.exception.TahuException: INTERNAL_ERROR
at org.eclipse.tahu.mqtt.TahuClient.publish(TahuClient.java:437)
```
Complete stacktrace
```auto
com.inductiveautomation.ignition.common.script.JythonExecException: Traceback (most recent call last): File "
at org.python.core.Py.JavaError(Py.java:547)
at org.python.core.Py.JavaError(Py.java:538)
at org.python.core.PyReflectedFunction.call(PyReflectedFunction.java:192)
at com.inductiveautomation.ignition.common.script.ScriptManager$ReflectedInstanceFunction.call(ScriptManager.java:552)
at org.python.core.PyObject.call(PyObject.java:433)
at org.python.core.PyObject.call(PyObject.java:437)
at org.python.pycode._pyx290._publishEvent$5(:127)
at org.python.pycode._pyx290.call_function()
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:150)
at org.python.core.PyFunction.call(PyFunction.java:426)
at org.python.pycode._pyx290.publish_conv_event$2(:25)
at org.python.pycode._pyx290.call_function()
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:306)
at org.python.core.PyBaseCode.call(PyBaseCode.java:158)
at org.python.core.PyFunction.call(PyFunction.java:437)
at org.python.pycode._pyx316.main$1(:111)
at org.python.pycode._pyx316.call_function()
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:168)
at org.python.core.PyFunction.call(PyFunction.java:437)
at org.python.pycode._pyx420.onStart$1(
at org.python.pycode._pyx420.call_function(
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:306)
at org.python.core.PyFunction.function ___call__ (PyFunction.java:474)
at org.python.core.PyFunction.call(PyFunction.java:469)
at org.python.core.PyFunction.call(PyFunction.java:464)
at com.inductiveautomation.ignition.common.script.ScriptManager.runFunction(ScriptManager.java:846)
at com.inductiveautomation.ignition.common.script.ScriptManager.runFunction(ScriptManager.java:828)
at com.inductiveautomation.ignition.gateway.project.ProjectScriptLifecycle$TrackingProjectScriptManager.runFunction(ProjectScriptLifecycle.java:832)
at com.inductiveautomation.sfc.elements.steps.StepScriptRunner.invoke(StepScriptRunner.java:62)
at com.inductiveautomation.sfc.elements.steps.StepScriptRunner.invoke(StepScriptRunner.java:40)
at com.inductiveautomation.sfc.elements.steps.action.ActionStep.activateStep(ActionStep.java:50)
at com.inductiveautomation.sfc.elements.StepContainer.onActivateRequested(StepContainer.java:145)
at com.inductiveautomation.sfc.fsm.element.ElementInactive.action(ElementInactive.java:35)
at com.inductiveautomation.sfc.fsm.element.ElementInactive.action(ElementInactive.java:8)
at com.inductiveautomation.sfc.fsm.StateContext.lambda$handleEvent$0(StateContext.java:49)
at com.inductiveautomation.sfc.api.ExecutionQueue$ThrowableCatchingRunnable.run(ExecutionQueue.java:146)
at com.inductiveautomation.sfc.api.ExecutionQueue$PollAndExecute.run(ExecutionQueue.java:120)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: org.python.core.PyException: org.eclipse.tahu.exception.TahuException: org.eclipse.tahu.exception.TahuException: INTERNAL_ERROR
... 46 common frames omitted
Caused by: org.eclipse.tahu.exception.TahuException: INTERNAL_ERROR
at org.eclipse.tahu.mqtt.TahuClient.publish(TahuClient.java:437)
at com.cirruslink.mqtt.engine.gateway.EngineRPCImpl.publishImpl(EngineRPCImpl.java:60)
at com.cirruslink.mqtt.engine.common.EngineAbstractScriptModule.publish(EngineAbstractScriptModule.java:30)
at jdk.internal.reflect.GeneratedMethodAccessor495.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at org.python.core.PyReflectedFunction.call(PyReflectedFunction.java:190)
... 43 common frames omitted
Caused by: org.eclipse.tahu.exception.TahuException: MQTT client: ME-5383d9f5-8085-485d is not connected
at org.eclipse.tahu.mqtt.TahuClient.publish(TahuClient.java:434)
```
**And finally, the TahuClient warning that is thrown _after_ the SFC are aborted**
```auto
org.eclipse.paho.client.mqttv3.MqttException: Unable to connect to server
at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:80)
at org.eclipse.paho.client.mqttv3.internal.ClientComms$ConnectBG.run(ClientComms.java:724)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.base/java.net.PlainSocketImpl.waitForConnect(Native Method)
at java.base/java.net.PlainSocketImpl.socketConnect(Unknown Source)
at java.base/java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.base/java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.base/java.net.SocksSocketImpl.connect(Unknown Source)
at java.base/java.net.Socket.connect(Unknown Source)
at org.eclipse.paho.client.mqttv3.internal.TCPNetworkModule.start(TCPNetworkModule.java:74)
... 2 common frames omitted
```
.
.
**Any support on how to trap this exception to prevent upsteam MQTT (RMQ) broker crashes from propagating to Ignition SFCs would be extremely helpful!**
---
### Author:  [@prince.cyril](https://forum.cirrus-link.com/u/prince.cyril)
#### Post date: [October 25, 2023, 6:19pm UTC](https://forum.cirrus-link.com/t/mqtt-engine-internal-error-crashes-ignition-project/446/2 "2023-10-25T18:19:32Z")
> [@christiankyte-bright](#):
>
> gnition SFCs are being aborted due
We have projects which has similar configuration as you described and I am eager to know what would be the solution to this matter.
Do you think this problem is something Inductive Automation would be better off at handling since it has to do with SFC depenencies ?
---
### Author:  [@wes.johnson](https://forum.cirrus-link.com/u/wes.johnson)
#### Post date: [October 31, 2023, 2:14pm UTC](https://forum.cirrus-link.com/t/mqtt-engine-internal-error-crashes-ignition-project/446/3 "2023-10-31T14:14:28Z")
What happens if you just try to catch all Exceptions and not just java.lang.Exception? i.e. just use ‘except’.