How To Fix MC421 - Number of key fields was limited to maximum number &

SAP Error Message - Details

• Message type: E = Error

• Message class: MC - Aggregate: views, matchcodes, lock objects

• Message number: 421

• Message text: Number of key fields was limited to maximum number &

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.

Unfortunately, there isn't any extra information in this error notice.

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Smart SAP Assistant

• What is the cause and solution for SAP error message MC421 - Number of key fields was limited to maximum number & ?

  The SAP error message MC421, which states "Number of key fields was limited to maximum number &," typically occurs in the context of SAP's Material Management (MM) or Logistics Information System (LIS) when there is an issue with the configuration of key fields in a data structure or report.
  Cause:
  The error is generally caused by exceeding the maximum number of key fields allowed in a particular data structure or report. In SAP, certain data structures have a predefined limit on the number of key fields that can be used. When you attempt to create or modify a report, query, or data structure that exceeds this limit, the system generates this error message.
  Solution:
  To resolve the MC421 error, you can take the following steps:
  
  
  Review Key Fields: Check the configuration of the report or data structure you are working with. Identify the key fields that have been defined and see if you can reduce the number of key fields being used.
  
  
  Modify the Report/Query: If you are using a custom report or query, consider modifying it to use fewer key fields. This may involve changing the selection criteria or aggregating data differently.
  
  
  Consult Documentation: Refer to SAP documentation or help resources to understand the specific limits for the data structure you are working with. This can provide insights into how many key fields are allowed.
  
  
  Check for Updates: Ensure that your SAP system is up to date. Sometimes, newer versions of SAP may have different limits or improved functionality that could help mitigate this issue.
  
  
  Seek Help from SAP Support: If you are unable to resolve the issue on your own, consider reaching out to SAP support or your internal SAP team for assistance. They may have additional insights or solutions based on your specific configuration.
  
  
  Related Information:
  
  SAP Notes: Check SAP Notes related to the MC421 error for any specific patches or updates that may address the issue.
  Transaction Codes: Familiarize yourself with relevant transaction codes (like SE11 for Data Dictionary, SE80 for Object Navigator) that can help you analyze and modify data structures.
  Performance Considerations: Reducing the number of key fields can also improve the performance of reports and queries, so it is beneficial from both a functional and performance perspective.
  
  By following these steps, you should be able to address the MC421 error and continue with your work in SAP.