Initialized key for &1

What causes this issue?

You have initialized the key of an entity of type &V1&. This is not
allowed.

System Response

The system uses the old key &V2&.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.