Inquiry Regarding 404 and 403 Errors with Azure FrontDoor Classic Cache

Question

Inquiry Regarding 404 and 403 Errors with Azure FrontDoor Classic Cache

Lucas 40

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:

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.
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.
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.

enter image description here

KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-12T10:53:18.7366667+00:00
@Lucas

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

Can you let me know the following,

You said that you noticed this issue after creating a new domain

Is this issue happening only with new domain?

Or you are able to reproduce this at different times.

It is possible that the content hasn't had time to propagate throughout the POP servers.

Are you able to reproduce this now?

Cheers,

Kapil
Lucas 40 Reputation points

2023-09-13T06:45:07.04+00:00
@KapilAnanth-MSFT

I apologize for the delayed response. Thank you for your response. Here is a summary of the additional information:

I encountered 404 errors on Azure Front Door Classic cached paths, specifically when newly creating a domain (endpoint). These errors occur intermittently for both JS and CSS files.

I am creating the domains using the Azure SDK, and in recent instances, when creating a new domain, requests for js/css files returned 404 errors. This issue can be reliably reproduced.

Our usage of Azure Front Door involves multiple domains using the same cache routing rule. In other words, the js or css files that are cached already exist. The 404 errors occur only when adding a new domain.

Thank you once again for your prompt attention to this matter. We appreciate your assistance in resolving this issue and look forward to your further guidance. If you require any additional information or have any questions, please do not hesitate to reach out.

Best regards,

Lucas
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-13T07:27:55.2266667+00:00
@Lucas

Thanks for your detailed explanation.

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 : https://learn.microsoft.com/en-us/azure/cdn/cdn-troubleshoot-endpoint#cause

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.

Let me know if this is incorrect.

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.

However, if you have a scenario where the issue is reproducible for a second time, (i.e., after the propogation was successful or for an existing rule/domain without any updates ), please do let us know and we can troubleshoot this incident.

Cheers,

Kapil
Lucas 40 Reputation points

2023-09-13T09:09:13.9666667+00:00

@KapilAnanth-MSFT

Thank you for your response.

You are absolutely correct. The issue occurs when I create a new domain and then add this new domain to an existing rule, essentially updating a cache rule. Your response has been immensely helpful to us.

We truly appreciate your prompt and informative assistance.

Best regards,

Lucas
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-13T09:20:48.8033333+00:00

@Lucas

You are most welcome.

I have summarized my comments and posted it as a new answer.

I would highly appreciate if you could Accept the answer and close this thread

Original posters help the community find answers faster by identifying the correct answer.

Thanks,

Kapil
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-14T08:39:21.2366667+00:00

@Lucas

Just checking in to see if the below answer helped. If this answers your query, please don’t forget to click "Accept the answer" and Up-Vote for the same, which might be beneficial to other community members reading this thread. And, if you have any further query do let us know.

Thanks,

Kapil

KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-12T10:53:18.7366667+00:00

@Lucas

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

Can you let me know the following,

You said that you noticed this issue after creating a new domain

Is this issue happening only with new domain?

Or you are able to reproduce this at different times.

It is possible that the content hasn't had time to propagate throughout the POP servers.

Are you able to reproduce this now?

Cheers,

Kapil
Lucas 40 Reputation points

2023-09-13T06:45:07.04+00:00

@KapilAnanth-MSFT

I apologize for the delayed response. Thank you for your response. Here is a summary of the additional information:

I encountered 404 errors on Azure Front Door Classic cached paths, specifically when newly creating a domain (endpoint). These errors occur intermittently for both JS and CSS files.

I am creating the domains using the Azure SDK, and in recent instances, when creating a new domain, requests for js/css files returned 404 errors. This issue can be reliably reproduced.

Our usage of Azure Front Door involves multiple domains using the same cache routing rule. In other words, the js or css files that are cached already exist. The 404 errors occur only when adding a new domain.

Thank you once again for your prompt attention to this matter. We appreciate your assistance in resolving this issue and look forward to your further guidance. If you require any additional information or have any questions, please do not hesitate to reach out.

Best regards,

Lucas
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-13T07:27:55.2266667+00:00

@Lucas

Thanks for your detailed explanation.

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 : https://learn.microsoft.com/en-us/azure/cdn/cdn-troubleshoot-endpoint#cause

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.

Let me know if this is incorrect.

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.

However, if you have a scenario where the issue is reproducible for a second time, (i.e., after the propogation was successful or for an existing rule/domain without any updates ), please do let us know and we can troubleshoot this incident.

Cheers,

Kapil
Lucas 40 Reputation points

2023-09-13T09:09:13.9666667+00:00

@KapilAnanth-MSFT

Thank you for your response.

You are absolutely correct. The issue occurs when I create a new domain and then add this new domain to an existing rule, essentially updating a cache rule. Your response has been immensely helpful to us.

We truly appreciate your prompt and informative assistance.

Best regards,

Lucas
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-13T09:20:48.8033333+00:00

@Lucas

You are most welcome.

I have summarized my comments and posted it as a new answer.

I would highly appreciate if you could Accept the answer and close this thread

Original posters help the community find answers faster by identifying the correct answer.

Thanks,

Kapil
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-14T08:39:21.2366667+00:00

@Lucas

Just checking in to see if the below answer helped. If this answers your query, please don’t forget to click "Accept the answer" and Up-Vote for the same, which might be beneficial to other community members reading this thread. And, if you have any further query do let us know.

Thanks,

Kapil

Answer 1

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 : https://learn.microsoft.com/en-us/azure/cdn/cdn-troubleshoot-endpoint#cause

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.

Thanks,

Kapil

Please Accept an answer if correct.

Original posters help the community find answers faster by identifying the correct answer

Lucas 40 Reputation points

2023-09-14T08:48:21.87+00:00

Thank you very much. I really appreciate it
KapilAnanth-MSFT 23,331 Reputation points Microsoft Employee

2023-09-14T08:56:14.6433333+00:00

@Lucas,

You are welcome

Thanks for your continued contribution on Q&A and appreciate much for taking the time to share your feedback.

Cheers,

Kapil

Inquiry Regarding 404 and 403 Errors with Azure FrontDoor Classic Cache

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