Unknown server tag 'asp:Chart'. 最最最简单解决办法。

直接贴上代码

<?xml version="1.0"?>
<!--
  有关如何配置 ASP.NET 应用程序的详细信息，请访问
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
<system.webServer>
  <validation validateIntegratedModeConfiguration="false" />
  <handlers>
   <remove name="ChartImageHandler" />
   <add name="ChartImageHandler" preCondition="integratedMode" verb="GET,HEAD,POST"
    path="ChartImg.axd" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
  </handlers>
 </system.webServer>
 <system.web>
<customErrors mode="Off"/>
<httpHandlers>
   <add path="ChartImg.axd" verb="GET,HEAD,POST" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    validate="false" />
  </httpHandlers>
  <compilation debug="true" targetFramework="4.0">
<assemblies>
<add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/></assemblies></compilation>
<pages validateRequest="false">
   <controls>
    <add tagPrefix="asp" namespace="System.Web.UI.DataVisualization.Charting"
     assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
   </controls>
  </pages>
<httpRuntime requestValidationMode="2.0" useFullyQualifiedRedirectUrl="true" maxRequestLength="1024000" executionTimeout="900"/>
<sessionState timeout="60"></sessionState>
</system.web>
<connectionStrings>
<add name="conn" connectionString="server=;database=;uid=sa;pwd=;pooling=true;min pool size=5;max pool size=512;connect timeout = 20;" providerName="System.Data.SqlClient"/>
</connectionStrings>
<appSettings>
  <add key="MaxAllowUploadFileSize" value="1024000000" />
  <add key="AllowUploadFileType" value="doc|docx|rar|xls|xlsx|txt|mp4" />
  <add key="org.winic.service2.Service" value="http://service2.winic.org/Service.asmx" />
  <add key="ChartImageHandler" value="storage=file;timeout=20;" />
 </appSettings>
</configuration>

请将红色部分改为自己的链接字符串，也可以不要。看你的情况。