Material &, unit &, layout module &, version &: No basic variant exists

What causes this issue?

You have set the indicator for excluding the material in a variant of
the assignment of the material to a layout module. This is allowed only
in layout module variants if a basic variant also exists for it for the
same shelf section placement. As no basic variant exists, the material
cannot be excluded in the 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.