DirectLine invoke postActivity returns 502 in Network though bot processes successfully

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Posted on by BestYuan

I am using Direct Line to send feedback data from the frontend to a bot using `postActivity` with an `invoke` activity.

Here is the code I’m using:

directLine.postActivity({
    type: 'invoke',
    name: 'message/submitAction',
    value: {
        actionName: 'feedback',
        actionValue: {
            feedback: { feedbackText: feedbackText || defaultFeedbackText },
            reaction: reaction
        },
        activityId: activityId
    },
    from: { id: user.employeeId, name: user.userName }
}).subscribe(
    id => console.log('Feedback sent, activityId:', id),
    error => console.error('Error sending feedback:', error)
);

Observed Behavior

The bot successfully receives and processes the feedback
Data (feedback text, reaction, etc.) is correctly stored
The subscribe callback does not always trigger an error
However, in the browser Network tab, the request consistently returns:

502 Bad Gateway

Expected Behavior

Since the bot processes the request successfully, I would expect an HTTP 200 OK instead of 502
Ideally, no error should appear in the Network tab

Constraints

I do NOT have access to the bot backend code (it is managed / wrapped by another team or service)
I can only make changes on the frontend

Questions

Is this a known behavior of Direct Line when using invoke activities without an explicit response from the bot?
Is there any way from the frontend to prevent or suppress the 502 response?
Would switching from invoke to message be a recommended workaround in such cases?
Is there any configuration in Direct Line that can avoid this behavior?

Additional Notes

The issue seems related to missing or improper invokeResponse from the bot
Functionality is not affected, but the 502 response is confusing and undesirable in production

Any insights or recommended best practices would be greatly appreciated.

Categories:

Calling actions from Copilot Studio

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Nivedipa-MSFT Microsoft Employee on at

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Hello ZY-19010544-0,
The 502 error occurs as expected because an 'invoke' action requires an invokeResponse from the bot; if it's missing, Direct Line returns a 502 error.

Solution: Update the type from 'invoke' to 'event'. Since events are fire-and-forget, the bot doesn't need to respond, and you won't encounter a 502 error. The bot will still receive the data, and no backend changes are necessary.

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BestYuan 63 on at

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@Nivedipa-MSFT Thank you very much for your reply.
I have already used event, but only increased the number of reactions. For reactions>comments, there is no response.
How can I customize the implementation of submitting feedback?

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Nivedipa-MSFT Microsoft Employee on at

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Hello BestYuan,
Thank you for the update.

Just to clarify, reactions and comments are processed differently. Reactions (messageReaction activity) are managed through onReactionsAdded, while comments are not a standard Direct Line activity type.

To collect custom feedback (both reactions and comments): You can use an Adaptive Card with Action.Submit (instead of invoke), including thumbs-up/down options and a text field for comments. Then, handle the submitted data in your bot's onMessage handler. This approach avoids the 502 error and allows you to manage the feedback process directly.

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BestYuan 63 on at

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@Nivedipa-MSFT Thank you very much.
Could you tell me how to actually operate it? Or how to make changes based on my code?
Actually, I have a customized page. If I use Adaptive Card, how should I write the code for my bot?

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Nivedipa-MSFT Microsoft Employee on at

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Hello BestYuan,
Could you please refer below document:
Designing Adaptive Cards for your app - Teams | Microsoft Learn

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