# OpcNotificationFailedEventArgs Class

> Reference: Provides the event data for the NotificationFailed and NotificationFailed events.

<span class="api-meta">since v2.57</span>

<dl class="api-definition">
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx.client">Opc.UaFx.Client</a></dd>
<dt>Assembly</dt>
<dd>Opc.UaFx.Advanced.dll</dd>
<dt>Package</dt>
<dd>Opc.UaFx.Advanced v2.59.0</dd>
<dt>Members</dt>
<dd><a href="./members">OpcNotificationFailedEventArgs Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Provides the event data for the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/notificationfailed) and [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#notificationfailed) events.

## Syntax

<div class="api-signature" data-lang="csharp">

```csharp
public class OpcNotificationFailedEventArgs : EventArgs
```

</div>

<div class="api-signature" data-lang="vbnet">

```vbnet
Public Class OpcNotificationFailedEventArgs
    Inherits EventArgs
```

</div>

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → [EventArgs](https://learn.microsoft.com/dotnet/api/system.eventargs) → **OpcNotificationFailedEventArgs**

## Remarks

A notification message fails to be received if the response delivering it cannot be processed, for example because a value of a data type in it cannot be decoded. The data changes and events of such a message do not reach the [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#datachangereceived) and [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#eventreceived) events.

A OpcNotificationFailedEventArgs instance is first passed to the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#notificationfailed) event of the [Subscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/members#subscription) the message belongs to. In case there no handler will set [Handled](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/members#handled) to the value true, the instance is passed to the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/notificationfailed) event of the owner of the [OpcSubscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/). A message whose subscription is not known is passed to the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/notificationfailed) event only.

## Properties

| Name | Description |
|---|---|
| [Exception](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/members#exception) | Gets the exception which describes why the notification message failed to be received. |
| [Handled](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/members#handled) | Gets or sets a value indicating whether the event handler has completely handled the event or whether the system should continue its own processing. |
| [Subscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/members#subscription) | Gets the [OpcSubscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/) the notification message belongs to. |

Inherits members from [EventArgs](https://learn.microsoft.com/dotnet/api/system.eventargs).

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.57–v2.59 |