Problem

-- why such out of sequence occur messages ?

"the message is not next in sequence order but a timeout has expired
and the message was released"

or

"the message was received twice, or it was received too late,
and a timeout made the message with higher sequence number available for read and commit"

Resolution

* it occurs when the "Stop-out-of_seq-messages" is set (you can check in System Profile Manager -> Environment -> Out of sequence action

* according to the development guide https://docs.axway.com/bundle/B2Bi_231_DeveloperGu..., such errors occur when the message has been delayed (for instance because the system was overloaded, or restarted). That is the expected behavior

"The sequence identifier and sequence number are used to set the processing order of a message.
This order is taken into account an all the activities that have sequencing enabled.
When a message from a given sequence arrives in the input queue of a sequencing enabled activity
that message is delayed until all messages with lower sequence number are processed and removed
from that queue.
When a queue is processing messages in sequence one of the following errors can occur"