Why is the reference for ConfigurationErrorsException missing from my .Net 3.0 application?
<p>I have a .NET 3.0 Winform Application with a corrupt user.config file causing system config errors.</p>

<p>I wanted to improve handle these errors, similar to how it's done in <a href="http://www.codeproject.com/Articles/30216/Handling-Corrupt-user-config-Settings" rel="nofollow">this example</a> on CodeProject. </p>

<p>To use '</p>

<p>However, when I try and use the 'ConfigurationErrorsException' to get the name of corrupted file I receive the following error:</p>

<pre><code>The type or namespace name 'ConfigurationErrorsException' could not be found (are you missing a using directive or an assembly reference?)  
</code></pre>

<p>I have only seen this error previously where there were .NET framework conflicts.
The project has the target framework .NET 3.0. The <code>ConfigurationErrorsException</code> was <a href="https://msdn.microsoft.com/en-us/library/system.configuration.configurationerrorsexception(v=vs.80).aspx" rel="nofollow">added in 2.0</a>, so I didn't think there would be a framework conflict there.</p>

<p>The version 3.0 documentation is lacking compared to other versions and does say:</p>

<blockquote>
  <p><a href="https://msdn.microsoft.com/en-us/library/system.configuration.configurationerrorsexception(v=vs.85).aspx" rel="nofollow">The current value is not one of the EnableSessionState values.</a></p>
</blockquote>

<p>Which I'm not entirely sure what that implies (the documentation for <a href="https://msdn.microsoft.com/en-us/library/system.web.configuration.pagessection.enablesessionstate(v=vs.85).aspx" rel="nofollow">EnableSessionState</a> lead to more confusion rather than less).</p>

<ul>
<li><strong>Why does the program fail to build, with a type or namespace missing error?</strong></li>
<li><strong>Is this related to targeting .NET 3.0?</strong></li>
<li>If so, <strong>Is there an alternative for .NET 3.0?</strong></li>
</ul>

<p><strong>EDIT:</strong>
I have made sure to include 'using System.Configuration' at the top of my page. The total list of usings is:</p>

<pre><code>using System;
using System.Collections.Generic;
//using System.Linq;
//using System.Threading.Tasks;
using System.Configuration;
using System.Windows.Forms;
using System.Threading;
using ProjectName.Properties;
using System.Security.Permissions;
using Microsoft.Win32;
</code></pre>