title: Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0 Error
body: <p>My .NET site is working fine on Localhost. But, on my Server. I get this error.</p>
  
  <blockquote>
    <p>"Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'."</p>
  </blockquote>
  
  <p>(Can't post screenshot, due to Stack Overflow policy)</p>
  
  <p>It's something to do with asp:ScriptManager. I have used it before on the same server, but now, it's showing an error.</p>
  
  <p>PS: When I remove Scriptmanager, the code runs fine.</p>
  
  <p>Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272</p>