Power Platform Community Forum Thread Details

I am encountering an issue with a custom connector that implements a webhook trigger, where the unsubscribe (DELETE) request does not follow the expected execution path.

The third-party API I am integrating with requires additional authentication handling. This logic is implemented in a script.csx file and delivered as part of the custom connector.

The webhook subscription (creation) request behaves as expected:

Returns HTTP 201 Created
Includes a valid absolute URL in the 'Location' header
Executes the custom connector pipeline, including script.csx
Applies authentication and connection parameter values correctly

However, the unsubscribe (DELETE) request behaves differently:

The request is issued outside of the custom connector processing pipeline
The script.csx logic is not executed
The connector’s authentication configuration and connection parameter values are not applied
The request is sent as a raw HTTP DELETE call without any authentication artifacts

As a result, the target API rejects the request due to missing authentication.

Additional observations

The DELETE request is only triggered in the following scenarios:

When the custom connector is turned off
When the Power Automate flow is deleted

However, the DELETE request is not triggered when:

The webhook trigger item (flow unit) is removed from the flow

Expected behavior

The unsubscribe (DELETE) request should be processed through the same custom connector pipeline as the subscription request
The script.csx logic should be executed
The configured authentication and connection parameter values should be applied
The request should include all required authentication artifacts

Actual behavior

The unsubscribe (DELETE) request bypasses the custom connector pipeline entirely
No custom logic (script.csx) is executed
No authentication or connection values are applied
The request is sent as an unauthenticated HTTP DELETE call, leading to failure

Impact

This behavior makes it impossible to correctly implement webhook cleanup for APIs that:

Require authenticated DELETE operations
Rely on custom authentication flows implemented via connector logic

Questions

Is this behavior expected for webhook unsubscribe operations in custom connectors?
If so, how are authenticated DELETE operations intended to be implemented when the connector pipeline is not executed?
If not, can this be considered a platform limitation or defect, and are there any recommended workarounds?

Categories:

Connector development

Using connectors

Using flows