How To Fix MC718 - Foreign key &-& (reference to external field)

SAP Error Message - Details

• Message type: E = Error

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

• Message number: 718

• Message text: Foreign key &-& (reference to external field)

What causes this issue?

A foreign key which is to be used for a join was defined so that a
foreign key field comes from another table. This table is not one of the
base tables of the view.

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?

This constellation is not allowed for database views and help views,
since in both cases there is no way to assign sensible values to the
external field.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message MC718 - Foreign key &-& (reference to external field) ?

  The SAP error message MC718, which states "Foreign key &-& (reference to external field)," typically occurs in the context of Material Management (MM) or Production Planning (PP) modules when there is an issue with data integrity related to foreign key relationships in the database.
  Cause:
  
  Foreign Key Violation: This error usually indicates that there is a foreign key constraint violation. This means that the system is trying to reference a value in a table that does not exist in the related table.
  Missing Data: The specific value that is being referenced may not exist in the corresponding table, leading to this error.
  Configuration Issues: There may be issues with the configuration of the foreign key relationships in the database schema.
  Data Inconsistency: There could be inconsistencies in the data due to manual entries, data migration, or other processes that have not maintained referential integrity.
  
  Solution:
  
  Check Data Integrity: Verify that the data you are trying to enter or process exists in the related table. For example, if you are referencing a material number, ensure that the material exists in the Material Master (MARA) table.
  Review Foreign Key Relationships: Check the foreign key relationships in the database schema to ensure they are correctly defined and that the referenced fields are correctly populated.
  Data Correction: If you find that the referenced data is missing, you may need to create the necessary entries in the related table or correct any erroneous entries.
  Transaction Logs: Review transaction logs or change logs to identify any recent changes that may have led to this inconsistency.
  Consult Documentation: Refer to SAP documentation or help resources for specific guidance on the tables and fields involved in the error.
  Debugging: If you have access to development tools, you can debug the transaction to see exactly where the error is occurring and what data is being processed.
  
  Related Information:
  
  Transaction Codes: You may want to use transaction codes like SE11 (Data Dictionary) to check table definitions and relationships, or SE16 (Data Browser) to view the data in the relevant tables.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message. SAP frequently updates its knowledge base with solutions to common problems.
  User Forums: Consider visiting SAP community forums or user groups where similar issues may have been discussed, and solutions shared.
  
  If the problem persists after following these steps, it may be beneficial to consult with your SAP Basis or technical team for further investigation.