Configure the system fallback topic in Power Virtual Agents


There is additional information available for people using Power Virtual Agents (preview).

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During a conversation, a Power Virtual Agents bot triggers the appropriate topic based on the user's input. If the bot can't determine the user's intent, it prompts the user again. After two prompts, the bot escalates to a live agent through the system Escalate topic.

In some scenarios, you might want to customize how the bot behaves when user input doesn't trigger any topic. For example, you can build a catchall topic to capture unrecognized user intent, or use a topic to call back-end systems or route to existing services.

Customize these fallback behaviors by adding the system Fallback topic. You can also customize the Fallback topic itself, similar to most other system topics.

This topic also includes the unique variable UnrecognizedTriggerPhrase to capture the unrecognized input.


Add a system fallback topic

  1. On the top pane, select Settings Settings icon. , and then go to the System fallback tab.

  2. Select "+Add".

Open System fallback settings.

A system fallback topic is added. The bot will go to this topic when it can't find an appropriate topic or doesn't understand the user's input.

A new option will appear on the Settings pane under the System fallback section: Go to fallback topic, which lets you customize the topic.

Customize the system fallback topic

After you add the system fallback topic, you can open it by selecting Go to fallback topic on the Settings pane.

You'll also see the Fallback topic listed in the topic list.

Fallback in the topic list.

When you open this topic in the authoring canvas, you'll see that the default fallback topic contains two nodes: a Message node that rephrases the user input and an Escalate node that redirects to a live agent.

Fallback topic default content.

You can customize this topic as with any other system topic. You can also use the *UnrecognizedTriggerPhrase variable that stores the user input the bot couldn't understand. For example, you can use the variable as an input and pass it to a Power Automate flow or Bot Framework skill.


The system fallback topic doesn't have a trigger phrase.

Reset system fallback behavior by deleting the fallback topic

To reset the system fallback behavior and return it to its default behavior, go to Settings and then System Fallback. In the System fallback section, select Delete to remove the fallback topic.

Delete the fallback topic.


This will remove the fallback topic and any changes you made to it.