Inquiry Regarding 404 and 403 Errors with Azure FrontDoor Classic Cache

Lucas 40 Reputation points

Dear Azure QA Team,

I hope this message finds you well. I would like to seek clarification and assistance regarding certain issues I have encountered with Azure FrontDoor Classic. Below is a summary of the current situation and my expectations:

  1. After creating a new domain, I've noticed that JavaScript (js), CSS, and other resources occasionally result in prolonged 404 errors lasting between 10 to 30 minutes, lasting between 10 to 30 minutes, before returning to normal with a 200 status code.
  2. As depicted in the screenshot, the presence of "Backend Host Name N/A" suggests that these requests are entirely processed by FrontDoor Classic, without any requests reaching the backend (origin) servers.
  3. I couldn't find any documentation explaining why FrontDoor Classic's cache route occasionally returns 404 or even 403 errors. Specifically, I'd appreciate insights into why this happens and how to mitigate it.

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Azure Front Door
Azure Front Door
An Azure service that provides a cloud content delivery network with threat protection.
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Accepted answer
  1. KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

    Hi @Lucas

    Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

    When you create a new domain, it will take some time for it to propagate across the infrastructure.

    The reasons are documented here for CDN :

    and the same applies to a classic AFD as well.

    I take it that you are,

    • Creating a new domain and a new Rule for it
    • And then using an existing backend in the Rule.

    If your case is specific to "domains newly created, and the issue is reproducible for the first few minutes " , I would say this is to be expected.

    • This is because, as you can see, the Cache policies are updated along with Rules and not with individual backend
    • So, if you are creating a new Rule or updating a rule, it is going to take some time to propagate across the infrastructure even when the backend is not updated/changed.

    Please let us know if we can be of any further assistance here.



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