Custom App.config section causing configuration load error

Question

I am using a custom configuration section in my app.config file to automatically email certain administrators when an error in the application occurs based on Jan Remunda's post here: How to create custom config section in app.config?

App.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>

  <configSections>
    <section name="ErrorEmailer" type="EmailTester.ErrorEmailer" />
  </configSections>

  <ErrorEmailer>
    <SmtpServer address="mail.smtphost.com" />
    <FromAddress address="from@host.com" />
    <ErrorRecipients>
      <ErrorRecipient address="example@example.com" />
      <ErrorRecipient address="example@example.com" />
    </ErrorRecipients>
  </ErrorEmailer>
</configuration>

And I have added these configuration elements:

public class ErrorRecipient : ConfigurationElement
{
    [ConfigurationProperty("address", IsRequired = true)]
    public string Address
    {
        get
        {
            return this["address"] as string;
        }
    }
}

public class SmtpServer : ConfigurationElement
{
    [ConfigurationProperty("address", IsRequired = true)]
    public string Address
    {
        get
        {
            return this["address"] as string;
        }
    }
}

public class FromAddress : ConfigurationElement
{
    [ConfigurationProperty("address", IsRequired = true)]
    public string Address
    {
        get
        {
            return this["address"] as string;
        }
    }
}

This Configuration Element Collection:

public class ErrorRecipients : ConfigurationElementCollection
{
    public ErrorRecipient this[int index]
    {
        get
        {
            return base.BaseGet(index) as ErrorRecipient;
        }
        set
        {
            if (base.BaseGet(index) != null)
            {
                base.BaseRemoveAt(index);
            }
            this.BaseAdd(index, value);
        }
    }

    public new ErrorRecipient this[string responseString]
    {
        get { return (ErrorRecipient)BaseGet(responseString); }
        set
        {
            if (BaseGet(responseString) != null)
            {
                BaseRemoveAt(BaseIndexOf(BaseGet(responseString)));
            }
            BaseAdd(value);
        }
    }

    protected override ConfigurationElement CreateNewElement()
    {
        return new ErrorRecipient();
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((ErrorRecipient)element).Address;
    }
}

And this Configuration Section:

public class ErrorEmailer : ConfigurationSection
{

    public static ErrorEmailer GetConfig()
    {
        return (ErrorEmailer)System.Configuration.ConfigurationManager.GetSection("ErrorEmailer") ?? new ErrorEmailer();
    }

    [ConfigurationProperty("ErrorRecipients")]
    [ConfigurationCollection(typeof(ErrorRecipients), AddItemName = "ErrorRecipient")]
    public ErrorRecipients ErrorRecipients
    {
        get
        {
            object o = this["ErrorRecipients"];
            return o as ErrorRecipients;
        }
    }

    [ConfigurationProperty("SmtpServer")]
    public SmtpServer SmtpServer
    {
        get
        {
            object o = this["SmtpServer"];
            return o as SmtpServer;
        }
    }

    [ConfigurationProperty("FromAddress")]
    public FromAddress FromAddress
    {
        get
        {
            object o = this["FromAddress"];
            return o as FromAddress;
        }
    }
}

But I get a "Configuration system failed to initialize" error when running the program and trying to run this:

var config = ErrorEmailer.GetConfig();
Console.WriteLine(config.SmtpServer.Address);

Timothy Shields · Accepted Answer · 2013-09-03T17:57:12.223

The configSections element must be the first child of the configuration element. Try this:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="ErrorEmailer" type="EmailTester.ErrorEmailer" />
  </configSections>
  <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
  <ErrorEmailer>
    <SmtpServer address="mail.smtphost.com" />
    <FromAddress address="from@host.com" />
    <ErrorRecipients>
      <ErrorRecipient address="example@example.com" />
      <ErrorRecipient address="example@example.com" />
    </ErrorRecipients>
  </ErrorEmailer>
</configuration>

Furthermore, you need to put the namespace and assembly of your custom config section type in your section element. Take this:

<section name="ErrorEmailer" type="EmailTester.ErrorEmailer" />

and add the assembly like this:

<section name="ErrorEmailer"
         type="EmailTester.ErrorEmailer, My.Containing.Assembly.Goes.Here" />

If you don't qualify the namespace path of your config type with the assembly it is contained in, .NET assumes you mean the System.Configuration assembly.

Thanks, that removed that issue but now I get "An error occurred creating the configuration section handler for ErrorEmailer: Could not load type 'EmailTester.ErrorEmailer' from assembly 'System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'." The format should be Namespace.ClassName for the type correct? — jokul, Sep 03 '13 at 17:52
Thanks a lot for quick, concise response, fixed everything. Will accept asap. — jokul, Sep 03 '13 at 17:55
Isn't it necessary that ErrorEmailer must be in the startup element? — Ozkan, Apr 06 '17 at 10:58

Custom App.config section causing configuration load error

1 Answers1