Issues with Azure Bot Service File Attachments Across Regions

Question

I am encountering an issue with file attachments in my application that uses the Azure Bot Service. When users upload and attempt to download files via the bot, the behavior differs across regions:

• From the region that the application is running, downloading the file fails with a 404 Not Found error.
• Trying locally from another region, the same file download works fine with a 200 OK response.

There are no apparent differences in implementation or permissions that would explain this discrepancy. Could this be related to regional storage policies, CDN behavior, or network restrictions? Any insights or troubleshooting suggestions would be greatly appreciated.

Answer 1

Hello Chris Karagiannis,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that you are having issues with Azure Bot Service File Attachments Across Regions.

These issues might be due to several factors and there are few ways to troubleshooting with the steps below:

1. Compare the exact URLs used in both regions. Check for differences in the domain, path, query parameters (like SAS tokens), container names, blob names.
2. Check the storage account's logs (Azure Storage Analytics logs or Azure Monitor) to see the requests coming in. See if the 404 requests are hitting the storage account and why they're failing. The logs might show the requested URL and the reason for the 404.
3. Verify the network configuration of the storage account. Ensure that it allows traffic from the problem region. Check firewall settings, virtual networks, and whether public access is allowed.
4. Check the replication status if using geo-redundant storage. Ensure that the data is replicated to the secondary region if that's the setup.
5. Test accessing the URL directly from a machine in the problem region. Use curl or a browser to see if the file is accessible. This can help determine if it's an application issue or a network/storage issue.
6. Check for any regional endpoints or DNS configurations that might be redirecting incorrectly.
7. Ensure that the SAS tokens (if used) are valid in terms of expiration time and permissions. Also, check the clock synchronization between the client and server.
8. Look into the possibility of the storage account being in a different region than the bot service, leading to higher latency or timeouts, but that might result in different errors.
9. Test with a new file upload in the problem region and see if it can be downloaded immediately, to check for replication delays.
10. Verify that the application code doesn't have any region-specific logic that might be altering the file paths or storage account references.

I hope these steps are helpful! Do not hesitate to let me know if you have any other questions or clarifications.

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Answer 2

Hi Chris Karagiannis,

The issue you're experiencing with file attachments in the Azure Bot Service could indeed be related to several factors, including regional storage policies, CDN behavior, or network restrictions. Here are some potential troubleshooting suggestions

• Ensure that the storage account used for file attachments is accessible from the region where your application is running. There may be restrictions or configurations that limit access based on the region.
• If you are using a Content Delivery Network (CDN), verify that the CDN is properly configured to serve content from the correct origin. Misconfigurations can lead to 404 errors if the CDN cannot find the requested file.
• Investigate any network restrictions or firewall settings that might be affecting access to the storage service from the region where the application is running.
• If your application is a web app, ensure that CORS is configured correctly on your Azure Storage account to allow requests from the domain where your application is hosted.
• Utilize Azure Monitor and logs to trace the requests made to the storage service. Look for any discrepancies in the request IDs or error messages that could provide more context on the failures.
• Kindly refer these Troubleshooting Azure Content Delivery Network endpoints that return a 404 status code
• https://learn.microsoft.com/en-us/troubleshoot/azure/azure-storage/blobs/alerts/troubleshoot-storage-client-application-errors?tabs=dotnet#the-client-is-receiving-http-404-not-found-messages

Hope this helps. Do let us know if you any further queries.

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