Missing Vary-Cookie makes pages uncachable (for Varnish)

[rommelfreddy]

Preconditions and environment

• Magento version: >= 2.4.8
• not logged in customer

Steps to reproduce

Just setup Varnish with the default-configurations

Expected result

Cacheable Pages, like CMS, Catalog and so on, should be cached and stored in the Varnish-Cache

Actual result

Magento will always make the response uncachable by calling Magento\Framework\App\Response:: setNoCacheHeaders

Additional information

In commit d6c05bd, logic was added to make the response uncacheable if the Vary cookie does not match the actual (generated) vary string.

While this makes sense in principle, it also causes all pages to become uncacheable whenever no Vary cookie is set — which is always the case on the very first request.

Additionally, this situation also occurs when Varnish requests the backend without sending the Vary cookie. As a result, this bug affects all ESI requests as well.

This issue should be treated with high priority, as it effectively prevents full-page caching with Varnish from functioning correctly.

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For anyone encountering this problem, I’ve created a temporary patch until an official fix is released: patch

Please use this patch with care and test your application thoroughly.

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @rommelfreddy. Thank you for your report.
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[m2-assistant]

Hi @engcom-November. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

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[m2-assistant]

Hi @engcom-Bravo. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.