Bill Baer /bɛːr/

So you downloaded the ULS Viewer and fired up on your SharePoint 2010 environment only to see something like this?

-—

System.TypeInitializationException: The type initializer for ‘UlsGump.AboutForm’ threw an exception. —> System.TypeLoadException: Could not load type ‘System.Reflection.CustomAttributeExtensions’ from assembly ‘mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’.

   at UlsGump.AboutForm..cctor()

   — End of inner exception stack trace —

   at UlsGump.MainForm.MainForm_Load(Object sender, EventArgs e)

   at System.Windows.Forms.Form.OnLoad(EventArgs e)

   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)

   at System.Windows.Forms.Control.CreateControl()

   at System.Windows.Forms.Control.WmShowWindow(Message& m)

   at System.Windows.Forms.Control.WndProc(Message& m)

   at System.Windows.Forms.Form.WndProc(Message& m)

   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

The problem lies in that the ULS Viewer (well mscorlib) is looking for the .NET 4 version of mscorlib.  Installing Microsoft .NET Framework Version 4.5 should resolve the issue.

SharePoint 2010 installs Microsoft .NET Framework Version 3.5 SP1 whereas SharePoint 2013 installs Microsoft .NET Framework Version 4.5.