我也有同样的问题。看到3.5和4.0解决方案感到沮丧。事实证明，您执行相同的操作，只需
<ConfigSections>在Web.config中的标记中添加几行即可。粘贴时，它应该是根目录下的第一个元素。
<configSections> <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"> <sectionGroup name="scripting" type="System.Web.Configuration.scriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"> <sectionGroup name="webServices" type="System.Web.Configuration.scriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"> <section name="jsonSerialization" type="System.Web.Configuration.scriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false"/> </sectionGroup> </sectionGroup> </sectionGroup></configSections>
然后添加实际
<system.web.extensions>部分：
<system.web.extensions> <scripting> <webServices> <jsonSerialization maxJsonLength="50000000"/> </webServices> </scripting></system.web.extensions>
