&1 should be same for all products in interchangeability group

What causes this issue?

You are trying to create or change an interchangeability group
containing products which do not have same value for the fields defined
in the field catalog.

System Response

System issues either a warning or an error.

How to fix this error?

Select products which have the same values for the fields that have
been included in the filed catalog while creating or changing an
interchangeability group.
You can maintain the field catalog in Customizing: <LS>SAP APO
Implementation Guide -> Advanced Planning and Optimization -> Master
Data -> Product Interchangeability -> Consistency Checks -> Maintain
Field Catalog</>.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.