How To Fix SL166 - System log message &1&2 is not defined

SAP Error Message - Details

• Message type: E = Error

• Message class: SL - System log

• Message number: 166

• Message text: System log message &1&2 is not defined

What causes this issue?

A function refers to a system log message, which is not known to the
system.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Analyze a part of the system log and use the system log messages there,
or check using transaction <NP>SE91</> (<LS>-> Tools -> CASE ->
Development -> Program maintenance -> System log messages -> List all
numbers</>) which messages actually exist.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message SL166 - System log message &1&2 is not defined ?

  The SAP error message SL166, which states "System log message &1&2 is not defined," typically indicates that the system is trying to reference a log message that has not been defined in the system. This can occur in various scenarios, such as during system operations, when processing transactions, or when executing certain programs.
  Cause:
  
  Missing Message Definition: The specific message that the system is trying to log does not exist in the message class or has not been defined in the system.
  Custom Development: If there are custom programs or enhancements that reference a message that has not been created, this error can occur.
  Transport Issues: If a transport request that includes message definitions has not been imported correctly, it may lead to missing messages.
  System Configuration: Incorrect configuration or settings in the system that affect logging can also lead to this error.
  
  Solution:
  
  Check Message Class: Use transaction SE91 to check the message class and ensure that the message number being referenced exists. If it does not exist, you may need to create it.
  Create Missing Messages: If the message is indeed missing, you can create it in the appropriate message class using transaction SE91. Make sure to provide the necessary text and attributes for the message.
  Review Custom Code: If the error is coming from custom code, review the code to ensure that it is referencing valid message numbers. Update the code to reference existing messages or create the necessary messages.
  Transport Management: If the issue is related to transport, ensure that all relevant transport requests have been imported correctly and that the message definitions are present in the target system.
  System Logs: Check the system logs (transaction SM21) for additional context or related errors that may provide more insight into the issue.
  
  Related Information:
  
  Transaction Codes:
  
  SE91: Message Class Maintenance
  SE80: Object Navigator (for checking custom programs)
  SM21: System Log
  
  
  SAP Notes: Search for relevant SAP Notes in the SAP Support Portal that may address this specific error or provide additional troubleshooting steps.
  Documentation: Review SAP documentation related to system logging and message handling for more detailed information on how messages are defined and managed.
  
  If the issue persists after following these steps, consider reaching out to SAP support or your internal SAP Basis team for further assistance.