Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information

Question

I am trying to create a new external content type using SharePoint Designer, whenever I am trying to add WCF connection I get an error message as "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information"

I am trying to add external content type to SharePoint Online using SPD 2013.

Answer 1

To troubleshoot the issue, check things below:

1. Close and re-open the SharePoint designer.

2. Clear SharePoint designer cache according to the article below.

How to Clear Your SharePoint Designer 2010/2013 Cache.

3. If the issue still exists, you could re-install the SharePoint designer.

Updated: I suggest you could submit a service request like the picture below.