更新web.config解决
<dependentAssembly><assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/><bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.0.0.0"/> </dependentAssembly>
找不到方法:“System.Collections.ObjectModel.Collection`1
