A serious error occurred while a LUW is being processed and the related queue has the following status in transaction SMQ1:
If the first LUW in an outbound queue cannot be processed due to a connection error ( CPIC error), then it is not only blocked for this queue but also for all other queues in which dependent LUWs are found.
All data for LUW dependencies and related queues is stored in the TRFCQOUT table.
The increasing qRFC tables lead to a 'data jam' and can cause database problems.
As soon as the problem is solved, all blocked queues are automatically processed further.
A backlog of this type can, for example, occur if a system or application exception occurs while executing a LUW in the inbound queue of the target system. In this case no automatic restart takes place. The system administrator or application administrator must solve the problem to restart the outbound queue manually.
If a system or application exception occurs while a qRFC LUW is being processed in the target system, the target system returns this error to the sending system. The status of the related LUW is updated according to the exception message in transaction SMQ1.
If an application exception occurs, and you are unable to determine the cause of the error, you must contact the relevant application group to solve the problem.
SAP recommends that you select queue names in such a way that it is clear which application component they belong to.
Solve the problem that caused the queue to become blocked.
Run transaction SMQ1.
Set the status of the related queue(s) using.
Note that the qRFC component itself never blocks a queue. If a queue has status STOP, then this status was set by a qRFC application or manually in transaction SMQ1.
The QOUT Scheduler is only reactivated if the block is removed by the application or manually using transaction SMQ1. If a queue is blocked for a long time with status STOP, and you are sure that the queue has not been manually blocked by SMQ1, check the affected application.
After resetting the queue status, the QOUT Scheduler restarts the affected queues and these can be processed after the cause of the error has been solved.
Detailed information on checking and changing queue status: