No valid MPN materials found

What causes this issue?

None of the <DS:GLOS.3526C020AFAB52B9E10000009B38F974>MPN materials</>
on the <DS:GLOS.3526C060AFAB52B9E10000009B38F974>approved manufacturer
parts list</> can currently be procured (possibly due to their being
blocked for various reasons, for example).

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?

Error message extract from SAP system. Copyright SAP SE.