The remote server returned an error: notfound when Silverlight calls WCF service

At The beginning of development, an exception like “The Remote Server returned an Error: NotFound.” was encountered.
The first time was because the service address was incorrectly filled in, that is, the wrong URI parameter was passed in when the EndpointAddress was created in Silverlight Application, and the exception disappeared when the correct modification was made.
But the exception was encountered again soon, and the address was found to be correct after checking. Also, the service method cannot be called correctly using the WcfTestClient tool. Therefore, the server was debugged, and it was found that abnormalities occurred in the running process of the server. The specific reason was that the Web.congfig of the server accidentally deleted the connectionString during re-editing, thus resulting in the exception of empty reference. But somehow, this error turns into a NotFound error on the client side?

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