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[BUG] Some cookies appear to be stuck (FF 86+ Strict Mode / cross-site protection / dynamic first party isolation)

See original GitHub issue

Describe the bug

It appears as if under certain conditions CAD was not able to remove eligible cookies on Firefox, even though it tries. Even though it appears consistently in my browser profile I found it difficult to exactly reproduce it in a new browser profile. Cookies got stuck there too, but not the same.

To Reproduce

Steps to reproduce the behavior:

  1. Go to a Google site (, Had it with Wikimedia cookies however too.
  2. Make sure you got cookies set.
  3. Close the tab.
  4. CAD should now attempt to clear the cookies in question.

Expected behavior

All eligible cookies should get removed.


Three attempts over four seconds


That screenshot should hopefully clearly show that CAD does determine these cookies as eligible for removal, but still fails to remove them

Your System Info

  • OS: Windows 8.1
  • Browser Info: Firefox 80
  • CookieAutoDelete Version: 3.4.0

Additional context

To be fair, it could be that is a general Firefox issue. With I don’t seem to be able to delete the cookies selectively either, I need to use Firefox own built-in cookie manager.

The cookies on “” are called CheckConnectionTempCookie. Are there any known issues in this area?

Issue Analytics

  • State:open
  • Created 3 years ago
  • Reactions:7
  • Comments:65 (29 by maintainers)

github_iconTop GitHub Comments

kennethtran93commented, Sep 30, 2021

An update from reveals that a patch to the extension API for ‘partitionKey’ (needed for cross-site protection buckets) is added for milestone Firefox 94. Once this available on Dev channel, I’ll plan some time to look into getting it working again. I can’t guarantee that I’ll have it ready before Firefox 94 is released.

kennethtran93commented, Nov 7, 2021

FF94 landed as the main release this week and after updating I’m running into this issue where CAD does not want to actually delete anything.
Has there been any progress with this issue with regards to FPI and custom (3rd party) blocking? @kennethtran93

The existing FPI (third party/cross-site tracking) option should still work. I’m working on the dynamic version (cross-site cookies). In the process of adding more info to the cookies so that you can select which partitioned cookie to keep/erase.

Read more comments on GitHub >

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