Invalid parameters for RFC to Landscape Directory

What causes this issue?

The call parameters for the RFC to the Landscape Directory are invalid.
The system installation number or the name of the database server
probably could not found.
Error text:
<NP>host: &v1&</>
<NP>license_number: &v2&</>

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?

Execute the action again that triggered this message.
If the exception still occurs, contact SAP Support. The message number
and the error text will be required to process your inquiry.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.