Matl &, unit &, layout mod. &, version &: Excl. in basic var. not allowed

What causes this issue?

You have set the indicator for excluding the material in a basic
variant of the assignment of the material to a layout module. This is
allowed only in layout module variants.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.