How To Fix USMD1049 - Data model &1, entity type &2, relationship &3: Cardinality is invalid

SAP Error Message - Details

• Message type: E = Error

• Message class: USMD1 - Datenmodel

• Message number: 049

• Message text: Data model &1, entity type &2, relationship &3: Cardinality is invalid

What causes this issue?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

To use cardinalities in relationships, the following conditions must be
met:
For relationships of the type <LS>Referencing</>, only the cardinalities
<LS>1:N</> and <LS>0:N</> are permitted.
For relationships of the type <LS>Qualifying and Foreign Key
Relationship</>, only the cardinality <LS>1:N</> is permitted.
For relationships of the type <LS>Leading</>, only the cardinalities
<LS>1:N</> and <LS>1:1</> are permitted. The following also applies to
the cardinality <LS>1:1</>:
The to-entity type must have either the <DS:DE.USMD_USAGE_TYPE>storage
and use type</> <LS>1</> without an assigned data element, or <LS>4</>.
The to-entity type may not appear in any other relationship of the type
<LS>Leading</> or <LS>Qualifying</> as a to-entity type.
At least one of the conditions has not been fulfilled.
ELSE
To use cardinalities in relationships, the following conditions must be
met:
For relationships of the type <LS>Referencing</>, only the cardinalities
<LS>1:N</> and <LS>0:N</> are permitted.
For relationships of the type <LS>Qualifying and Foreign Key
Relationship</>, only the cardinality <LS>1:N</> is permitted.
For relationships of the type <LS>Leading</>, only the cardinalities
<LS>1:N</> and <LS>1:1</> are permitted. The following also applies to
the cardinality <LS>1:1</>:
The to-entity type must have either the <DS:DE.USMD_USAGE_TYPE>storage
and use type</> <LS>1</> without an assigned data element, or <LS>4</>.
The to-entity type may not appear in any other relationship of the type
<LS>Leading</> or <LS>Qualifying</> as a to-entity type.
At least one of the conditions has not been fulfilled.
ELSE
<LS>1:N</> is the only cardinality allowed for the relationship types
<LS>Leading </>and <LS>Qualifying</>.

System Response

The data model cannot be saved or activated.

How to fix this error?

Enter a different relationship type or a different cardinality.
ELSE
Enter a different relationship type or a different cardinality.
ELSE
Specify a different relationship type or define <LS>1:N</> as the
cardinality.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.