How To Fix C1821 - Inconsistent characteristic value assignment

C1821 - Overview

• Message type: E = Error

• Message class: C1 - Characteristics maintenance messages

• Message number: 821

• Message text: Inconsistent characteristic value assignment

What causes this issue?

You want to change the value assigned to a characteristic. However, the
change causes inconsistency, so the new value is not allowed.
The inconsistency may be for the following reasons:
A precondition or selection condition is violated.
The characteristic is a single-value characteristic, and different
values have been set by constraints, actions, or procedures.
In classification, inconsistencies occur when you change the value set
of a characteristic if objects or classes have already been classified
with values from the previous value set (for example, in the case of a
configurable material or a generic material).

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?

Choose <PF>Inconsistencies</> to see what triggered the inconsistency.
You can also use the explanation facility for more information.
Delete the values that triggered the inconsistency.
You can only change or delete a value or value set that has already been
used to classify objects if you delete the existing allocations.

Error message extract from SAP system. Copyright SAP SE.

C1821 - Details

• The SAP error message C1821, which states "Inconsistent characteristic value assignment," typically occurs in the context of SAP's classification system. This error indicates that there is a mismatch or inconsistency in the assignment of characteristic values to a classification object, such as a material or a document.
  Causes of Error C1821
  
  Inconsistent Data: The characteristic values assigned to a classification object do not match the expected values defined in the classification system.
  Missing Characteristics: Required characteristics may not be assigned to the object, leading to inconsistencies.
  Incorrect Value Assignment: The values assigned to characteristics may not be valid or may not conform to the defined value range for those characteristics.
  Changes in Class Structure: If the class structure has been modified (e.g., characteristics added or removed), existing assignments may become inconsistent.
  Data Migration Issues: If data has been migrated from another system, inconsistencies may arise due to differences in classification setups.
  
  Solutions to Error C1821
  
  Check Characteristic Assignments: