Cannot create value assignment header; data is not saved

What causes this issue?

The system automatically creates a value assignment header for each
property to which you assign a value.
The system could not create the value assignment header.

System Response

The system cannot save the data you entered.

How to fix this error?

Exit the transaction and repeat the steps that led up to the error. If
the error continues to occur, notify your system administrator.

Error message extract from SAP system. Copyright SAP SE.