How To Fix MC757 - Selection/join from external field &-&

SAP Error Message - Details

• Message type: E = Error

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

• Message number: 757

• Message text: Selection/join from external field &-&

What causes this issue?

A join condition links a field of a table which was not included as
base table. This is only permitted in maintaenance views as an
exception, whereby the application program has to ensure that the field
is assigned the correctd values.

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?

For database and help views, only define join conditions for fields of
the base tables. Foreign keys referring to external fields cannot be
used in the definition of join conditions.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message MC757 - Selection/join from external field &-& ?

  The SAP error message MC757 typically occurs in the context of reporting or data extraction, particularly when there is an issue with the selection criteria or joins involving external fields in a query or report. This error indicates that there is a problem with the way the data is being accessed or joined, often due to missing or incorrect field definitions.
  Cause:
  
  Field Definition Issues: The external field being referenced may not be defined correctly in the data model or may not exist in the specified context.
  Join Conditions: There may be an issue with the join conditions between tables, especially if the external field is not properly linked to the main data source.
  Data Source Configuration: The data source may not be configured to include the external field, or there may be restrictions on accessing that field.
  Authorization Issues: The user may not have the necessary authorizations to access the external field or the related data.
  
  Solution:
  
  Check Field Definitions: Verify that the external field is correctly defined in the data model. Ensure that it exists and is accessible in the context of the report or query.
  Review Join Conditions: Examine the join conditions in the query or report. Ensure that the external field is properly linked to the relevant tables and that the join logic is correct.
  Data Source Configuration: Ensure that the data source is configured to include the external field. If necessary, update the data source settings to include the required fields.
  Authorization Check: Confirm that the user has the necessary authorizations to access the external field. If not, work with your SAP security team to grant the appropriate permissions.
  Debugging: If the issue persists, consider using transaction codes like SE11 (Data Dictionary) or SE80 (Object Navigator) to analyze the data model and identify any discrepancies.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to the error message MC757. SAP frequently updates its knowledge base with solutions for common errors.
  Documentation: Review the documentation for the specific module or transaction you are working with to understand the expected behavior and configuration settings.
  Community Forums: Engage with SAP community forums or user groups where similar issues may have been discussed. Other users may have encountered the same error and can provide insights or solutions.
  
  If the problem continues after following these steps, it may be beneficial to consult with your SAP support team or a technical consultant who can provide more in-depth analysis and assistance.