How To Fix CNV_OM_PRESEL036 - Preselection Scheduler is already running - start not allowed

SAP Error Message - Details

• Message type: E = Error

• Message class: CNV_OM_PRESEL - Messages for LT Object Based Preselection

• Message number: 036

• Message text: Preselection Scheduler is already running - start not allowed

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

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Smart SAP Assistant

• What is the cause and solution for SAP error message CNV_OM_PRESEL036 - Preselection Scheduler is already running - start not allowed ?

  The SAP error message CNV_OM_PRESEL036 indicates that the Preselection Scheduler is already running, and therefore, a new instance cannot be started. This error typically occurs in the context of data migration or conversion processes, particularly when using the SAP S/4HANA Migration Cockpit or similar tools.
  Cause:
  
  
  Concurrent Execution: The most common cause of this error is that the Preselection Scheduler is already executing a task. This can happen if:
  
  A previous instance of the scheduler has not completed yet.
  There is a manual or automated process that is trying to start the scheduler again while it is still running.
  
  
  
  System Lock: Sometimes, the system may have a lock that prevents the scheduler from being started again until the current process is finished.
  
  
  Solution:
  
  
  Check Running Processes: 
  
  Use transaction codes like SM37 (Job Monitoring) to check if there are any active jobs related to the Preselection Scheduler. If you find any, wait for them to complete or terminate them if they are stuck.
  
  
  
  Wait for Completion: If the scheduler is running a long process, it may be best to wait until it completes before attempting to start it again.
  
  
  System Logs: Check the system logs for any additional error messages or warnings that might provide more context about why the scheduler is still running.
  
  
  Restart the Scheduler: If you have confirmed that no other instances are running and you still receive the error, you may need to restart the relevant background jobs or the entire system if necessary.
  
  
  Consult Documentation: Refer to the SAP documentation or notes related to the specific migration or conversion process you are working on. There may be specific instructions or known issues related to the Preselection Scheduler.
  
  
  Contact SAP Support: If the issue persists and you cannot identify the cause, consider reaching out to SAP Support for assistance. They may have additional insights or patches available for your specific version of SAP.
  
  
  Related Information:
  
  Transaction Codes: Familiarize yourself with transaction codes like SM37 (Job Monitoring), SM21 (System Log), and ST22 (Dump Analysis) to help diagnose issues.
  SAP Notes: Search for relevant SAP Notes in the SAP Support Portal that may address this specific error or provide guidance on the Preselection Scheduler.
  Migration Cockpit: If you are using the SAP S/4HANA Migration Cockpit, ensure that you are following the recommended steps and guidelines for data migration.
  
  By following these steps, you should be able to resolve the CNV_OM_PRESEL036 error and successfully manage the Preselection Scheduler in your SAP environment.