I am not able to add web service in .net Core 3.1 project, while adding web service i am getting following error.

was not recognized as a known document type.
The error message from each known type may help you fix the problem:
The document at the url {my web service url} was not recognized as a known document type.
The error message from each known type may help you fix the problem:

The document at the url {my web service url} was not recognized as a known document type.
The error message from each known type may help you fix the problem:

• Report from ‘WSDL Document’ is ‘There is an error in XML document (1, 12014).’.
  • The empty string ” is not a valid local name.
    Parameter name: name
• Report from ‘XML Schema’ is ‘The root element of a W3C XML Schema should be and its namespace should be ‘http://www.w3.org/2001/XMLSchema’.’.
• Report from ‘DISCO Document’ is ‘Discovery document at the URL {my web service url} could not be found.’.
  • The document format is not recognized.
    Metadata contains a reference that cannot be resolved: ‘ {my web service url} ‘.
    The content type text/xml; charset=utf-8 of the response message does not match the content type of the binding (application/soap+xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly.

Thank You.

I tried it in dotnet web site project too,still facing same issue.