MQTT Modular Input: Does not start, receives error

[pau3bk]

MQTT Modular Input does not start.

Error Message is:

   Introspecting scheme=mqtt: script running failed (exited with code 1)
   Unable to initialize modular input "mqtt" defined inside the app "mqtt_ta": Introspecting scheme=mqtt: script running failed (exited with code 1)

I changed mqtt.py to log the Java call (see below).

When I start it from a command line, the error appears (not belonging to Java): ERROR Incorrect Program Usage
Nothing else. Any idea?

C:\Tools\jdk-12.0.1\bin\java -classpath C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\commons-codec-1.9.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\commons-logging-1.2.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpasyncclient-4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpasyncclient-cache-4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpclient-4.4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpclient-cache-4.4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpcore-4.4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\httpcore-nio-4.4.1.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\json.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\log4j-1.2.16.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\mqtt-client-0.4.0.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\mqttmodinput.jar;C:\Tools\Splunk\etc\apps\mqtt_ta\bin\lib\splunk_tlsv12.jar; -Xms64m  -Xmx64m  -Dsplunk.securetransport.protocol=tls com.splunk.modinput.mqtt.MQTTModularInput

[cbreezier]

This is very late, but I ran into the same error.

I saw a hint at https://community.splunk.com/t5/All-Apps-and-Add-ons/Unable-to-initialize-modular-input-quot-mqtt-qu...

I also found a page about troubleshooting add-ons: https://docs.splunk.com/Documentation/AddOns/released/Overview/Troubleshootadd-ons

Which allowed me to find the following log from the add-on for more information:

07-20-2020 06:43:40.050 +0000 ERROR ModularInputs - <stderr> Introspecting scheme=mqtt: java: symbol lookup error: java: undefined symbol: JLI_StringDup

And then I found this bug: https://bugs.launchpad.net/ubuntu/+source/openjdk-lts/+bug/1882208

So I downgraded to openjdk-8 and all is well for me (I was on openjdk-11). I see that you're running jdk-12, which is likely to be your problem.