IE 11 on Win10 Creators Update interprets Cache-Control: private differently than other IE 11 versions

Confirmed Issue #12246819 • Assigned to Taeksoo J.


Doug S.
Jun 5, 2017
This issue is public.
Reported by 5 people

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Steps to reproduce

IE 11.296.15063.0 (bundled with Win 10 Creators Update) treats Cache-Control: private response headers differently than other browsers including other IE 11 releases. It caches all responses with the private directive, refusing to request any URI twice.

As a result, none of our AngularJS apps work, since their REST requests to dynamic endpoints are now being cached. Our customer support team is beginning to receive calls of “F5 doesn’t work” and we have tracked it down to this.

The RFC 2616 spec is ambiguous about what a browser should do when it receives a private directive. A private (non-shared) cache MAY cache the response.

The IE11 Win10CU version appears to be treating that MAY from the RFC as “go ahead, should be fine” and is now caching the default responses from any of our REST endpoints. Once a URI has been requested from this build of IE11, it will never be requested again from the server.

Technically, this build of IE11 is still interpreting the RFC correctly, it just happens to now be different from all major browsers.

Our testing shows that the private directive works fine (browsers won’t cache the response) on:

  • Edge
  • Chrome
  • Firefox
  • IE 11 on Windows 7 (11.0.9600.18665)
  • IE 11 on Windows 10 build 1607 Anniversary edition (11.1198.14393.0)

It only breaks on the version of IE 11 that is bundled with Windows 10 Creators Update.

Our .NET backend is using ServiceStack for its REST endpoints, which return Cache-Control: private for any request by default. While we can and will change our default response headers (a bit expensive to deploy to all our customers servers in a timely manner), I think this change in caching behaviour may affect a number of other apps in subtle ways.

The IE11 team may need to consider reverting the behaviour change.


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    Comments and activity

    • Microsoft Edge Team

      Changed Assigned To to “James M.”

      Changed Assigned To to “Saty B.”

    • I think we have the same problem. IE 11.296.15063.0 refuses to download a fresh version of a JavaScript file even after clearing the temporary internet files, cookies etc.

    • We are seeing this (or a very similar) issue affecting some large clients too, with IE 11.413.15063.0

    • I’m experiencing the same issue using Windows 10 version 1703 (Build 15063.413) and IE 11.413.15063.0

      Is there an ETA for this?

    • Microsoft Edge Team

      Changed Status to “Confirmed”

      Changed Assigned To from “Saty B.” to “Robert Z.”

      Changed Assigned To from “Robert Z.” to “Taeksoo J.”

      Changed Assigned To from “Taeksoo J.” to “James M.”

    • Hello,

      Thank you for providing this information about the issue. When the Cache-Control is Private or No-Cache, IE11 doesn’t use a cache, but it does use a cache if it is Public. So, IE11 does honor Cache-Control: Private header, and it aligns to the expected behavior.

      Please reply to this case if you have more information for us to consider.

      Best Wishes,
      The MS Edge Team

    • Hi James,

      The intent may be that IE 11 doesn’t cache but it certainly is for us with our GET AJAX requests. When I test with IE 11 v11.371.16299.0 an HTTP response which includes the following header is returned from our ASP.NET MVC application:

      Cache-Control: private, s-maxage=0

      The next request to the same URL does not hit the server and IE 11 developer tools show that the response was Received "(from cache)".


    • Microsoft Edge Team

      Changed Assigned To to “James M.”

      Changed Assigned To to “wsdcfebrowsernni”

      Changed Status from “Confirmed”

      Changed Assigned To from “wsdcfebrowsernni” to “Taeksoo J.”

      Changed Status to “Confirmed”

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