Error in specification data server

What causes this issue?

During secondary data determination, data was requested from the SAP
System. This data is provided via a specification data server based on
a WWI generation server. An error occurred when the data from this WWI
generation server was generated.

System Response

The specification data server cannot provide the required data.

How to fix this error?

Notify your system administrator.
Check whether the specification data server was started for secondary
data determination. Test the RFC connection using transaction sm59.

Error message extract from SAP system. Copyright SAP SE.