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IT40467: FDC with Probe Id RM033006 and Message sequence number error AMQ9526E are generated when pipelining is enabled

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APAR status

  • Closed as program error.

Error description

  • When using a sender and receiver channel where pipelining is
    enabled in the qm.ini file, a failure data capture (FDC) record
    with probe ID RM033006 is
    generated along with message sequence number errors in the
    queue manager's error logs.  For example:
    Channel pipelining is enabled in qm.ini by setting
    PipeLineLength to a value greater than 1:
    An FDC record with the following information is generated:
    Probe Id          :- RM033006
    Application Name  :- MQM
    Component         :- rriReceiveData
    Program Name      :- amqrmppa
    Thread            :- XXXX    DUOWReceive
    QueueManager      :- QUEUE_MANAGER_NAME
    Major Errorcode   :- rrcE_PROTOCOL_ERROR
    Minor Errorcode   :- OK
    Probe Description :- AMQ9504E: A protocol error was detected
    for channel ''.
    This FDC header may show that the thread where the error occurs
    tagged as "DUOWReceive" which indicates that the channel is
    using "pipelining".
    Also in the queue manager's error logs, there will be message
    sequence number errors:
    AMQ9526E: Message sequence number error for channel
    The local and remote queue managers do not agree on the next
    message sequence
    number.  A message with sequence number XXXXXXXX has been sent
    when sequence
    number YYYYYYYY was expected. The remote host is
    Determine the cause of the inconsistency.  It could be that the
    information has become damaged, or has been backed out to a
    previous version.
    If the situation cannot be resolved, the sequence number can be
    manually reset
    at the sending end of the channel using the RESET CHANNEL
    These message sequence number errors may be accompanied by
    message loss.

Local fix

  • Turn off channel pipelining by setting PipeLineLength=1 in the
    Channels stanza of the qm.ini file.

Problem summary

  • ****************************************************************
    Those using the channel pipelining performance optimisation by
    PipeLineLength=2 in the Channels stanza of the qm.ini file, and
    who have applied a fix for APAR IT30074.
    IT30074 was included in and later LTS fix packs; and in
    9.1.3 CD and later CD releases, including
    This issue affects distributed queueing channels over a TCP
    link, which includes automatically defined cluster channel
    pairs, when PipeLineLength=2 is configured.
    This APAR does not affect client connections over a SVRCONN
    channel, as the PipeLineLength configuration attribute is not
    applicable to SVRCONN channels.
    Platforms affected:
    A defect introduced by APAR IT30074 meant that, when a network
    slow-down occurred,
    a pipelined receiver channel sent an invalid sequence of
    protocol flows.  These caused
    the sender channel to incorrectly commit a batch of messages
    while the receiver channel
    ended abnormally and backed out the batch.  When the channel
    restarted message
    sequence errors were reported, and in some circumstances
    messages were lost.

Problem conclusion

  • The defect has been fixed.
    The fix is targeted for delivery in the following PTFs:
    Version    Maintenance Level
    v9.1 LTS
    v9.2 LTS
    v9.x CD    9.3.0
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'

Temporary fix


APAR Information

  • APAR number


  • Reported component name

    MQ BASE V9.2

  • Reported component ID


  • Reported release


  • Status


  • PE




  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date


  • Closed date


  • Last modified date


  • 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

    MQ BASE V9.2

  • Fixed component ID


Applicable component levels

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"920","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
26 September 2022