App.Config: Order matters

Sep 23, 2011 in PROGRAMMING
1 min read

Note to self:

Within an App/Web.config in .NET… The startup node must be the last node…

Example: Create a plain WPF application from Visual Studio 2010, add an App.Config file, and try building Option 1 and Option 2 below.

Option 1:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup>
  <configSections />
</configuration>

This throws: The type initializer for 'System.Windows.Application' threw an exception.

Option 2:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections />
  <startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup>
</configuration>

Fine.

Do I want to read 2.5MB of C:\Program Files (x86)\Microsoft Visual Studio 10.0\Xml\Schemas\DotNetConfig.xsd? No.