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Why does Event Grid subscription validation fail permanently with no retry if endpoint is cold?

Michael McCarthy 0 Reputation points
2025-07-02T12:18:29.0533333+00:00

When creating an Azure Event Grid subscription to a WebHook or Azure Function endpoint, if the endpoint is temporarily unavailable (e.g., cold start, DNS delay), the validation request fails, and the subscription enters a provisioningState = "Failed" permanently.

This breaks deployment automation workflows (ARM, Bicep, Terraform) and has no recovery path — there's no retry, no way to manually trigger revalidation, and no system event to notify the user.

AWS SNS retries subscription confirmation for hours in the same scenario:

Is there a supported workaround or roadmap to improve this behavior?

This feels like a platform-level reliability bug rather than a feature gap.

GitHub issue for tracking:

https://github.com/Azure/azure-sdk-for-net/issues/51014

Azure Event Grid
Azure Event Grid
An Azure event routing service designed for high availability, consistent performance, and dynamic scale.

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  1. VenkateshDodda-MSFT 25,186 Reputation points Microsoft Employee Moderator
    2025-07-07T06:50:35.1466667+00:00

    @Michael McCarthy Thanks for posting your question in Microsoft QnA. apologize for any inconvenience caused on this.

    Since the endpoint is in cold state you are not able to deploy the event grid subscription using the Iac tools.

    To avoid this failure during the creation of the event grid subscription you can point the webhook endpoint to this dummy endpoint which is available in this site "https://webhook.site/#!/view/7c7bedf5-825c-4f16-967e-f26b2dad1ab3"

    Once the endpoint becomes active you can add another task in the template and by using this AzCLI cmdlets az eventgid topic event-subscription-create cmdlet

    Hope this helps, let me know if you have any further questions on this.

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