Unknown server tag 'asp:LinqDataSource'

June 18, 2012 ASP.NET Database C# Troubleshooting LINQ
If you're getting an error saying that the asp:LinqDataSource is unknown, you most likely is missing the declaration in your web.config file. To fix this:

  1. Open your web.config file and locate the <controls> block.
  2. Add the following element: <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.UI.WebControls" tagprefix="asp"> into the <controls&gt; block.
  3. Reload the page and see it working :)

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