You cannot change fact category &1; see long text

What causes this issue?

Data has already been stored in the system for this fact category. This
is why the system does not allow you to change the field name.

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?

If you want to change the field name for this fact category, you must
first delete all the fact values that reference this fact category.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.