IT31909: MQTT Channel ends unexpectedly due to NullPointerException

APAR status

• Closed as program error.

Error description

• The MQTT channel ends with an error in the log:
  
  AMQCO2001E: An error (probe: XR014005) occurred and a Failure
  Data Capture (FDC) file has been written to file 'MQXR2.FDC'.
  AMQCO1006I: Channel 'XXXXXXXX' has stopped
  
  and an FDC generated with details:
  
   Probe Id          :- XR014005
  
   java.lang.NullPointerException
  at
  com.ibm.mq.MQXRService.MQTTServerSessionV3.handleReceive(MQTTSer
  verSessionV3.java:258)
  at
  com.ibm.mq.MQXRService.HttpServerContext.handleReceive(HttpServe
  rContext.java:235)
  at
  com.ibm.mq.MQXRService.HttpServerContext.handleWebSocketFrame(Ht
  tpServerContext.java:174)
  at
  com.ibm.mq.http.HttpWireContext.receiveWebsocketFrame(HttpWireCo
  ntext.java:563)
  at
  com.ibm.mq.http.HttpWireContext.receive(HttpWireContext.java:196
  )
  at
  com.ibm.mq.communications.NonBlockingConnection.receive(NonBlock
  ingConnection.java:386)
  at
  com.ibm.mq.communications.NonBlockingWorker.run(NonBlockingWorke
  r.java:398)
  at java.lang.Thread.run(Thread.java:818)
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the MQTT channel service.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  The MQTT channel service may stop unexpectedly due to a
  NULLPOINTEREXCEPTION.  It will also generate a Failure Data
  Capture (FDC) file, which will contain the following java stack:
  
   java.lang.NullPointerException
     at
  com.ibm.mq.MQXRService.MQTTServerSessionV3.handleReceive(MQTTSer
  verSessionV3.java:258)
     at
  com.ibm.mq.MQXRService.HttpServerContext.handleReceive(HttpServe
  rContext.java:235)
     at
  com.ibm.mq.MQXRService.HttpServerContext.handleWebSocketFrame(Ht
  tpServerContext.java:174)
     at
  com.ibm.mq.http.HttpWireContext.receiveWebsocketFrame(HttpWireCo
  ntext.java:563)
     at
  com.ibm.mq.http.HttpWireContext.receive(HttpWireContext.java:196
  )
     at
  com.ibm.mq.communications.NonBlockingConnection.receive(NonBlock
  ingConnection.java:386)
     at
  com.ibm.mq.communications.NonBlockingWorker.run(NonBlockingWorke
  r.java:398)
     at java.lang.Thread.run(Thread.java:818)
  ```
  

Problem conclusion

• The code has been changed to avoid this Null Pointer Exception
  and prevent the unexpected shutdown of the MQTT channel service
  for this particular issue.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.11
  v9.1 LTS   9.1.0.8
  v9.2 LTS   9.2.0.2
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  IBM MQ BASE MP

• Fixed component ID

  5724H7271

Applicable component levels