After Creating Webapplication in VS 2010 and using Chart control you will Receive Following Errors Unknown server tag 'asp:chart'.
Visual Studio 2010 with .NET 4.0 not recognising System.Web.UI.DataVisualization.Charting
to Remove this error you need to make few changes in Web,config
Step 1:
Find the <system.web> Section in Web,config and make changes in 3 sections given below
<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>
<pages>
<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>
<compilation debug="true" targetFramework="4.0">
<assemblies>
<add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
</assemblies>
</compilation>
Step 2:
After This Find section <system.webServer>
and replace or merge with following contents
<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>
Step 3:
Add Reference for
System.Web.DataVisualization.dll