Maintenance status & not processed since not fully transferred

What causes this issue?

If the indicator <LS>Check required fields</> is not set when you
transfer data by <DS:GLOS.direct_input>direct input</> or when you
distribute data by <DS:GLOS.Application_Link_Enabling>application link
enabling</> (ALE), certain <DS:GLOS.maintenance_status>maintenance
statuses</> are not fully processed in create mode if not all required
fields contain entries. For more information, see the
<DS:DE.MD_MUSS_S>documentation</> for this indicator.

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

System Response

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.