不知道咋解决，关于Could not load type 'System.Runtime.CompilerServices.……
Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.TypeLoadException: Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Source Error:
Line 54: <body>
Line 55: [color=#FF0000]<form id="PublishTopicForm" method="post" runat="server">[/color]
Line 56: <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
Line 57: <table rules="all" id="publish-table">
Line 58: <thead></thead>
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272
百度了半天也没找到解决方案，这个错误一会出现一会不出现的，很是蛋疼，求解救。
只知道是ajax的
[解决办法]
dll加载失败，确定是否有，或者版本一致
