Azure – Static Website Not Returning 404.html Page

azure

I created an Azure static website following Microsoft's tutorial. Everything works, except that Azure doesn't return the 404.html page for HTTP 404 requests.

My static website settings:

Azure static website settings

When I navigate to a page that doesn't exist, these are the headers Azure returns:

HTTP/1.1 404 The requested content does not exist.
Content-Length: 1214
Content-Type: text/html
Server: Windows-Azure-Web/1.0 Microsoft-HTTPAPI/2.0
x-ms-error-code: WebContentNotFound
x-ms-request-id: 2680e62d-a01e-002a-7d48-de2087000000
x-ms-version: 2018-03-28
Date: Sat, 08 Feb 2020 06:25:27 GMT

Those headers are correct. But here's what shows in the browser:

funny characters returned by Azure

I've verified that my 404.html page works fine by navigating directly to that page:

404 page works in browser

If I use the 'Storage Explorer' I can also see that my 404.html file is in $web:

404.html is in Azure Blob storage

Yet Azure doesn't return that page for HTTP 404 errors.

Things I tried:

  • Different browsers (Firefox and Chrome). Got the same result.
  • Emptied browser cache.
  • Re-uploaded the 404.html page.
  • Searched online for people with the same problem (didn't found any).
  • Verified my static website settings against several online tutorials. It seems my settings are correct.

Update: Following Biren's suggestion I set the $web container to the 'Container' access level. After re-uploading my files the issue still remains. But the text in the browser looks different now:

changed text in browser

These are the returned HTTP headers for files not in the blob (unchanged from earlier and still proper 404 from what I can tell):

HTTP/1.1 404 The requested content does not exist.
Content-Length: 966
Content-Type: text/html
Server: Windows-Azure-Web/1.0 Microsoft-HTTPAPI/2.0
x-ms-error-code: WebContentNotFound
x-ms-request-id: 6bfc762c-b01e-0026-1113-dfb78f000000
x-ms-version: 2018-03-28
Date: Sun, 09 Feb 2020 06:38:03 GMT

Best Answer

I fixed the issue myself today. The software I use to upload my website by default Gzips every HTML file. This is pretty standard and good behaviour. Unfortunately, Azure Blob Storage 404 pages do not support Gzip encoding.

This limitation isn't documented, although there's a feedback request for Gzip encoding of 404 pages here.

So the solution is simple: when uploading the static website, Gzip all HTML pages except 404.html. As soon as I did that, my strange text on 404 pages disappeared and everything works fine now.

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