Exception when adding log4net config

Question

I am getting an error on the very first line of code in the App.cs file (which is creating a readonly variable). The error I am getting is:

A first chance exception of type 'System.TypeInitializationException' occurred in PresentationFramework.dll An unhandled exception of type 'System.TypeInitializationException' occurred in PresentationFramework.dll Additional information: The type initializer for 'System.Windows.Application' threw an exception.

This is the message popup I get in VS:

An unhandled exception of type 'System.TypeInitializationException' occurred in PresentationFramework.dll

Additional information: The type initializer for 'System.Windows.Application' threw an exception.

The only change I have made is adding this to my app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <startup> 
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/>
  </startup>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
  </configSections>
  <log4net>
    <appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender" >
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger [%ndc] - %message%newline" />
      </layout>
    </appender>
    <root>
      <level value="INFO" />
      <appender-ref ref="ConsoleAppender" />
    </root>
  </log4net>
</configuration>

Have you added a reference to `log4net` to the same project that contains this `app.config`? — Chris Ballard, Mar 23 '14 at 20:10
If yes, then can you copy and paste the full stack trace for this exception - that will help a lot — Chris Ballard, Mar 23 '14 at 20:11
@Chris - yes the reference is there. See edit for full exception details. — Cheetah, Mar 23 '14 at 20:15
@Prix - sorry I didn't think the rest was relevant as it was just the quoted bits that were causing the issues....however, I have now edited with the full config. — Cheetah, Mar 23 '14 at 20:25
@Ben make `` the first element and see if that works. In other words put it before ``. — Prix, Mar 23 '14 at 20:27
Next time do a little more research before posting the question, duplicate of [Why would adding an \*\*appSettings\*\* section to App.config cause an error in WPF application?](http://stackoverflow.com/questions/1223142/why-would-adding-an-appsettings-section-to-app-config-cause-an-error-in-wpf) — Prix, Mar 23 '14 at 20:36
Something is corrupted in your app.config (maybe you copy/paste some tags?) — Masciuniria, Oct 03 '18 at 11:00

score 22 · Accepted Answer · answered Mar 24 '14 at 17:22

The issue was that I had the <startup> xml node in the app.config file at the start rather than the end of the file. It needs to be the last thing in the app.config file.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  // lots of other stuff here...
  <startup> 
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/>
  </startup>
</configuration>

score 0 · Answer 2 · answered Jun 15 '20 at 10:04

0

I had same error. I found that <configSections> has to be the first element.

answered Jun 15 '20 at 10:04

Mario M.

416
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Exception when adding log4net config

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