1. Install the NuGet package

The best way to install Raygun4Net is to use the NuGet package manager. With the NuGet Visual Studio extension installed, right-click on your project and select “Manage NuGet Packages…” Make sure “Online” is highlighted in the left hand pane, then use the top right search box to find Mindscape.Raygun4Net and install it.

Alternatively, visit for instructions on installation using the package manager console.

2. Setup Raygun in Web.config

In your Web.config file, find configSections and add the following entry:

<section name="RaygunSettings" type="Mindscape.Raygun4Net.RaygunSettings, Mindscape.Raygun4Net"/>

Then reference it by adding the following line somewhere after the configSections tag. Your app API key is displayed when you create a new application in your Raygun account, or can be viewed in the “Application Settings”. RaygunSettings has many options which are explained further down this page.

<RaygunSettings apikey="YOUR_APP_API_KEY" />

3. Add the Raygun HTTP module to automatically send exceptions

Still in Web.config, set up the Raygun HTTP module. This is done slightly differently depending on what version of IIS you’re using. If in doubt, just try them both:

For IIS 6.0 (Or a fallback for using IIS 7.0 in classic mode), use system.web

    <add name="RaygunErrorModule" type="Mindscape.Raygun4Net.RaygunHttpModule"/>

For IIS 7.0, use system.webServer

    <add name="RaygunErrorModule" type="Mindscape.Raygun4Net.RaygunHttpModule"/>

The above set up will cause all unhandled exceptions to be sent to your Raygun account.

Manually sending exceptions

The above instructions will setup Raygun4Net to automatically detect and send all unhandled exception data. Sometimes you may want to send exceptions manually - either in an exception handler as an alternative to using the HTTP module, or to report handled exceptions from within a try/catch block.

To manually send exceptions, create an instance of the RaygunClient class. The default constructor will use the API Key that you set up in Web.config. Alternatively, you could use the constructor that takes an API Key if you need to send the exception to a different one of your Raygun applications, or if you didn’t set it in the config.

With the RaygunClient, you can call either the Send or SendInBackground methods. It’s important to note that SendInBackground should only be used for handled exceptions, rather than exceptions that will cause the application to crash - otherwise the application will most likely shutdown all threads before Raygun is able to finish sending. Both the Send and SendInBackground methods have many overloads for sending additional data which are explained in the various feature sections below.

Here’s an example of using a RaygunClient within the Application_Error handler. This is an alternative to using the HTTP module described in step 3 of the setup instructions above.

protected void Application_Error()
  var exception = Server.GetLastError();
  new RaygunClient().Send(exception);

Similarly, here’s how to manually send exceptions from a try/catch block:

  // Do something here that might go wrong
catch (Exception e)
  new RaygunClient().SendInBackground(e);

Throw exceptions to avoid missing stack traces

Sometimes you may have code that detects that something has gone wrong, but doesn’t actually throw an exception. If you want to log this to Raygun, it is tempting to just create a new exception instance and pass it through one of the RaygunClient send methods. Note however that a .NET exception needs to be thrown in order for its stack trace to be populated. So whenever you want to send a new exception instance to Raygun, make sure you are throwing the exception, then catch and send it from within a try/catch block as in the code example above. This will ensure that you log the stack trace which is useful for you to debug, and is used by Raygun to group exceptions.

Providing a custom RaygunClient to the HTTP module

The HTTP module mentioned in step 3 of the instructions above will use its own RaygunClient instance to send exceptions. If you need to use any of the features that require customizing a RaygunClient instance, then you can provide the HTTP module with your own RaygunClient as follows.

In your global HttpApplication class, create a static instance of RaygunClient, and set any options on it within your Application_Start method. The default constructor of RaygunClient will use the API Key that you set up in Web.config, or you can pass in an API key if you need to. Next, implement the IRaygunApplication interface, and in the single method that you need to implement - GenerateRaygunClient, simply return your RaygunClient instance. And that’s it - from now on, the HTTP module will use your RaygunClient returned from this method to send all unhandled exceptions.

public class Global : System.Web.HttpApplication, IRaygunApplication
  private static readonly RaygunClient _raygunClient = new RaygunClient();

  protected void Application_Start(object sender, EventArgs e)
    // Set any options on the client here

  public RaygunClient GenerateRaygunClient()
    return _raygunClient;

Modify or cancel messages

On a RaygunClient instance, attach an event handler to the SendingMessage event. This event handler will be called just before the RaygunClient sends an exception report - either automatically or manually. The event arguments provide the RaygunMessage object that is about to be sent. There are two different uses for this event handler:

  • Modify the message. You can make any changes you want to the RaygunMessage object such as removing, adding or changing values. Any changes that you make will affect the exception report that gets sent to Raygun.
  • Cancel the message. Sometimes you may get exceptions from parts of the application that you have no control over (such as 3rd party plugins) or due to issues that cannot be solved (such as various bot attacks). In this event handler, you can look through the properties of the RaygunMessage to determine if the exception is one that you don’t care about. If so, you can then set e.Cancel = true to prevent Raygun4Net from sending it.

Here is an example of cancelling a message. This assumes that the Raygun HTTP module is being used, and so includes the IRaygunApplication interface technique described above.

public class Global : System.Web.HttpApplication, IRaygunApplication
  private static readonly RaygunClient _raygunClient = new RaygunClient();

  protected void Application_Start(object sender, EventArgs e)
    // Attach the event handler:
    _raygunClient.SendingMessage += RaygunClient_SendingMessage;

  private void RaygunClient_SendingMessage(object sender, RaygunSendingMessageEventArgs e)
    // This is an example of cancelling a message:
    if (e.Message.Details.Request.Url.StartsWith("/api/v2/breachedaccount/"))
      e.Cancel = true;

  public RaygunClient GenerateRaygunClient()
    return _raygunClient;

Note that if an exception occurs within your SendingMessage event handler, Raygun4Net will detect this and send the new exception as well as the original exception that was being processed. When processing the new exception, the event handler will not be called again in order to avoid an infinite loop.

Custom grouping

When exception reports are sent to Raygun, they get grouped using our classification logic. We improve this logic every now and then, but sometimes you may come across scenarios where exceptions reports are grouped together or put into separate groups where you were not expecting. This can be from cases we are not yet handling, scenarios that are specific to your application, or unique grouping preferences you have. Raygun4Net lets you provide your own custom grouping logic before exceptions are sent to Raygun.

To use the custom grouping key feature, start by getting the RaygunClient instance used to send your exception reports and attach an event handler to the CustomGroupingKey event. This event gets fired before the SendingMessage event described in the section above. The event arguments provide both the original Exception object and the RaygunMessage object that is about to be sent. In the event handler, you can use whatever logic you want to build a grouping key (string) for the given exception. When the key is ready, set it to the CustomGroupingKey property of the event arguments. Exceptions that end up with the same key will be grouped together. Grouping keys have a limit of 100 characters.

Unless you have extreme grouping logic that needs to be applied to all exceptions, we recommend that you only apply custom grouping logic to scenarios that we are not handling for you. You can include checks in your event handler for certain types of exceptions for example, and only create a custom grouping key for them. Exceptions that you don’t provide a custom grouping key for will be grouped in Raygun using the grouping classifiers we provide.

Here is an example of providing a custom grouping key. This assumes that the Raygun HTTP module is being used, and so includes the IRaygunApplication interface technique described above.

public class Global : System.Web.HttpApplication, IRaygunApplication
  private static readonly RaygunClient _raygunClient = new RaygunClient();

  protected void Application_Start(object sender, EventArgs e)
    // Attach the event handler:
    _raygunClient.CustomGroupingKey += RaygunClient_CustomGroupingKey;

  private void RaygunClient_CustomGroupingKey(object sender, RaygunCustomGroupingKeyEventArgs e)
    // This example simply performs pure message based grouping on basic Exception instances:
    if (e.Message.Details.Error.ClassName.Equals("Exception"))
      string key = e.Exception.Message;
      e.CustomGroupingKey = key;

  public RaygunClient GenerateRaygunClient()
    return _raygunClient;

Note that if an exception occurs within your CustomGroupingKey event handler, Raygun4Net will detect this and send the new exception as well as the original exception that was being processed. When processing the new exception, the event handler will not be called again in order to avoid an infinite loop.

Exclude errors by HTTP status code

If using the HTTP module, then you can exclude errors by their HTTP status code by providing a comma separated list of status codes to ignore in the configuration. For example if you wanted to exclude errors that return the I’m a teapot response code, you could use this configuration:

<RaygunSettings apikey="YOUR_APP_API_KEY" excludeHttpStatusCodes="418" />

Exclude errors that originate from a local origin

To prevent Raygun4Net from sending exceptions that originate from a local origin (your debug/development machine), set the excludeErrorsFromLocal attribute to true as seen in the code below. This is useful if you find that everyone in your team sending exceptions from their local machines is noisy and pointless. This option is a convenient alternative to using Web.config transforms to do the same thing.

<RaygunSettings apikey="YOUR_APP_API_KEY" excludeErrorsFromLocal="true" />

Remove sensitive request data

By default, Raygun4Net will send all form-fields, headers, cookies and server-variables in the current HTTP request. If you have sensitive data in an HTTP request that you wish to prevent being transmitted to Raygun, you can provide a list of possible named values to remove:

<RaygunSettings apikey="YOUR_APP_API_KEY" ignoreFormFieldNames="password,creditcard,cv2" />

Four attributes are available, to remove values from these four properties:

  • ignoreFormFieldNames (ignores values from HttpRequest.Form)
  • ignoreHeaderNames (ignores values from HttpRequest.Headers)
  • ignoreCookieNames (ignores values from HttpRequest.Cookies)
  • ignoreServerVariableNames (ignores values from HttpRequest.ServerVariables)

Or specify them in code with the following multi-parameter method:

_raygunClient.IgnoreFormFieldNames("password", "creditcard", "cv2");

Setting any of these four options to * will cause Raygun4Net to ignore all values in that category, so none of them are sent to Raygun. Also, by placing * before, after or at both ends of a name, Raygun4Net will use that as an ends-with, starts-with or contains condition respectively when determining what to ignore.

Medium Trust

When integrated into an ASP.NET project running on Azure or shared web hosts running under Medium Trust, the provider can be configured to run correctly using this:

<RaygunSettings apikey="YOUR_APP_API_KEY" mediumTrust="true" />

User tracking

Providing user information will allow your Raygun dashboard to display the number of unique users that each exception has affected. This is a huge help with prioritising issues to solve that have the largest impact. You can provide whatever user information that will help you solve issues, but make sure to abide by any privacy policies that your company follows. At the very least, providing a unique guid will allow you to see the number of users that are affected by each error. If available, you could provide an ID that is meaningful to you such as a database ID. This could help you to look up information at your end that aids in solving issues. If you are able to provide a name and contact details, you’d be able to contact customers to let them know that issues they’ve encountered are being worked on, or have been solved.

There are a few ways to provide user information, the simplest of which is to set the User property of the RaygunClient instance to an identifier of your choosing:

_raygunClient.User = "";

If a single identifier string isn’t enough, you can set the UserInfo property instead to provide more information:

_raygunClient.UserInfo = new RaygunIdentifierMessage("")
  IsAnonymous = false,
  FullName = "Robbie Robot",
  FirstName = "Robbie"

Here are all the available RaygunIdentifierMessage properties:

  • Identifier (passed into the constructor) is the unique identifier from your system for this user.
  • IsAnonymous is a flag indicating whether the user is logged in (or identifiable) or if they are anonymous. An anonymous user can still have a unique identifier.
  • Email The user’s email address. If you use email addresses to identify your users, feel free to set the identifier to their email and leave this blank. We will use the identifier as the email address if it looks like one, and if no email address is specified in this field.
  • FullName The user’s full name.
  • FirstName The user’s first (or preferred) name.
  • UUID A device identifier. Could be used to identify users across devices, or machines that are breaking for many users.

Another way to provide the user information is to use one of the Send or SendInBackground overloads which has a RaygunIdentifierMessage as a parameter. The overloads include ‘tags’ and ‘custom data’ parameters (see below) which you can set as null if you don’t need to use them. This should be used if you only get the user information when a crash occurs, or if the user information is not fixed, or in heavily threaded scenarios where you have a separate RaygunClient instance for each thread.

_raygunClient.SendInBackground(exception, null, null, new RaygunIdentifierMessage("") { IsAnonymous = false, FullName = "Robbie Robot", FirstName = "Robbie" });


An overload of Send and SendInBackground allows you to include a list of tags with each manually sent exception:

_raygunClient.Send(exception, new List<string>() { "tag1", "tag2" });

Exceptions can be searched in your Raygun dashboard by tags that you’ve included.

Custom data

You can include key-value custom data using an overload of the Send or SendInBackground method. Values can be primitive types or rich object structures. All properties of objects and their children will be sent to Raygun. Cyclic object references will be detected and handled as appropriate, and any property getter that produces an exception will cause that property value to be displayed as the exception message.

_raygunClient.Send(exception, null, new Dictionary<string, object>() { { "key", "value" } });

The second parameter is the list of tags (mentioned above) which can be null if you don’t have tags for the current exception.

Version numbering

By default, Raygun4Net will attempt to send the assembly version of your project with each report. If this is unavailable, or if you need to provide your own custom version value, you can do so by setting the ApplicationVersion property of the RaygunClient.

_raygunClient.ApplicationVersion = "";

Alternatively, you can set the applicationVersion in Web.config as follows. If both are set, the property mentioned above takes precedence over the Web.config setting.

<RaygunSettings apikey="YOUR_APP_API_KEY" applicationVersion="" />

Stripping wrapper exceptions

If you have common outer exceptions that wrap a valuable inner exception which you’d prefer to group by, you can specify these by using the following multi-parameter method:


The above example will cause MyWrapperException instances to be stripped away and never sent to Raygun. Instead, only the inner exception of any stripped exceptions will be sent. By default HttpUnhandledException and TargetInvocationException will always be stripped - see below to override this behavior.

AggregateException support (Only applicable to .NET 4.0 and higher)

AggregateException is a special case as they can hold multiple inner exceptions. By stripping AggregateException instances using the method described above, all inner exceptions will be sent to Raygun as separate exception reports. That way, each inner exception can be put into the appropriate individual groups and managed separately.

Prevent wrapper exception stripping

If you want to prevent Raygun4Net from stripping the default wrapper exceptions (HttpUnhandledException and TargetInvocationException) then you can call the multi-parameter RemoveWrapperExceptions method as shown below. This can also be useful if you’ve used the above instructions to cause Raygun4Net to strip a wrapper exception type that you later don’t want to strip within a single execution of the app.


Proxy settings

The Raygun4Net provider uses the default Windows proxy settings (as set in Internet Explorer’s Connection tab, or Web.config) when sending messages to Raygun. If your proxy requires authentication credentials, you can provide these by setting the ProxyCredentials property of your RaygunClient instance:

_raygunClient.ProxyCredentials = new NetworkCredential("user", "pword");

Signed version

A version of Raygun4Net that has been signed with a strong name is available for those who need it. While following the set up instructions above, simply install the Mindscape.Raygun4Net.Signed NuGet package.

The provider is open source and available at the Raygun4Net repository.