client found response content type of text/html...

架設一個內部網站,出現這個錯, 很怪...
client found response content type of 'text/html; charset=utf-8', but expected 'text/xml'. the request failed with the error message:
...
section or group name 'system.web.extensions' is already defined. updates to this may only occur at the configuration level where it is defined.

最後找到原因
是iis root 的目錄下放一個web.config, 大概是衝到了吧...