问题
I have a WPF client application which calls multiple ASMX webservices I keep on getting 401 authentication errors.
Sometimes for whatever reason one succeeds whereas the other one fails but then for some reason one works then the other one fails...Have no idea what the reason is.
One of the service needs to do a double hop and it was working earlier during the day and for some reason now has stopped working I do not believe I changed anything.
I Followed http://social.technet.microsoft.com/Forums/windowsserver/en-US/c9239a89-fbee-4adc-b72f-7a6a9648331f/401-unauthorized-access-is-denie d-due-to-invalid-credentials?forum=winserversecurity
following the suggestion
IIS 7 was difficult for figuring out why i was getting the 401 - Unauthorized: Access is denied due to invalid credentials... until i did this...
1.) Open iis and select the website that is causing the 401
2.) Open the "Authentication" property under the "IIS" header
3.) Click the "Windows Authentication" item and click "Providers"
4.) For me the issue was that Negotiate was above NTLM. I assume that there was some kind of handshake going on behind the scenes, but i was never really authenticated. I moved the NTLM to the top most spot, and BAM that fixed it.
and it initially worked, however once I closed down fiddler the problems came back
来源：https://stackoverflow.com/questions/19806533/client-calling-multiple-asmx-services