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SameSite Updates

Adding `SameSite=None; Secure` to your cookies? Check the list of incompatible clients here.

Latest update: Oct 2, 2019

All updates:

Launch Timeline

Last updated Oct 3, 2019.

  • Early October, 2019: Experimental SameSite-by-default and SameSite=None-requires-Secure behavior launched to 50% of users on Chrome Canary and Dev (Chrome Canary and Dev versions 78+). Windows and Mac users on domain-joined devices and Chrome OS users on enterprise-registered devices will be excluded from the experiment. Chrome 78 Beta users will not receive the experimental behavior.
  • October 31, 2019: Chrome 79 Beta released. Experiment extended to 50% of Chrome 79 Beta users, including domain-joined and enterprise-registered devices. Policies to manage the experimental behavior (see below) will be available on Chrome 79.
  • February 4, 2020: Chrome 80 Stable released. SameSite-by-default and SameSite=None-requires-Secure become default behavior for all users on Stable.


Oct 2, 2019

In response to feedback from users and enterprise customers, we are deferring the experimental Beta launch of the "SameSite=Lax by Default" and "SameSite=None requires Secure" features from Chrome 78 Beta to Chrome 79 Beta. Users of Chrome 78 Beta will not experience any change or disruption in cookie behavior.

When the experiment is launched to Chrome 79 Beta users, domain-joined or enterprise-registered machines will be included in the experiment. Instead of excluding them from the experiment entirely, policies will be made available in Chrome 79 to manage the experimental behavior. This will provide extra time for administrators to configure and test the policies in advance of the Stable launch in Chrome 80.
One policy will allow administrators to specify a list of domains on which cookies should be handled according to the legacy behavior (LegacySameSiteCookieBehaviorEnabledForDomainList), and a second policy will provide the option to set the global default to legacy SameSite behavior for all cookies (LegacySameSiteCookieBehaviorEnabled). More details about these policies will follow in future enterprise release notes before the Chrome 79 release.
These features will still become the default behavior on Stable starting in Chrome 80.



Sept 30, 2019


To test whether your sites may be affected by the SameSite changes:

  1. Go to chrome://flags and enable #same-site-by-default-cookies and #cookies-without-same-site-must-be-secure. Restart the browser for the changes to take effect.

  2. Test your sites, with a focus on anything involving federated login flows, multiple domains, or cross-site embedded content. Note that, because of the 2 minute time threshold for the "Lax+POST" intervention, for any flows involving POST requests, you may want to test with and without a long (> 2 minute) delay.

  3. If your site stops working:

    • Try turning off #cookies-without-same-site-must-be-secure. If this fixes the issue, you need to set `Secure` on any `SameSite=None` cookies your site may be relying upon. (This may require upgrading HTTP sites to HTTPS.)
    • Try turning off both flags. If this fixes the issue, you need to identify the cookies being accessed in a cross-site context and apply the attributes `SameSite=None` and `Secure` to them. See "SameSite cookies explained" for more information. If you are not the developer of the site, please reach out to the developer and/or vendor who authored the site.
    • For flows involving POST requests, if a short delay (< 2 minutes) works but a long delay (> 2 minutes) does not work, you will also need to add `SameSite=None` and `Secure` to the relevant cookies if the operation in question may take longer than 2 minutes. Note that the 2-minute window for "Lax+POST" is a temporary intervention and will be removed at some point in the future (some time after the Stable launch of Chrome 80), at which point cookies involved in these flows will require `SameSite=None` and `Secure` even if under 2 minutes.
If you are an IT administrator managing a Chrome deployment for your organization, policies will temporarily be made available to maintain Chrome's existing behavior for your users. This is to give enterprises extra time to roll out and test changes. You have two options:
  1. (Recommended) Apply the LegacySameSiteCookieBehaviorEnabledForDomainList policy to the specific domains on which cookies require legacy behavior.
  2. (Less recommended due to security and privacy implications) Apply the LegacySameSiteCookieBehaviorEnabled policy to revert all cookies to legacy behavior. 
These policies will be made available starting in Chrome 80. Chrome 79. (See Oct 2, 2019 update.)


Sept 26, 2019

Starting in Chrome 80, cookies that do not specify a SameSite attribute will be treated as if they were SameSite=Lax with the additional behavior that they will still be included in POST requests to ease the transition for existing sites. Cookies that still need to be delivered in a cross-site context can explicitly request SameSite=None, and must also be marked Secure and delivered over HTTPS. We will provide policies if you need to configure Chrome Browser to temporarily revert to legacy SameSite behavior.


This section is obsolete: See Oct 2, 2019 update.

While experiments for this change will be rolling out to Chrome 78 Beta users, the Beta SameSite experiment rollout will exclude Windows and Mac devices that are joined to a domain and Chrome OS devices that are enterprise-registered. Beta users on Linux, iOS, Android, and Android Webview will also not be affected by the experiments at this time. For Chrome Beta users unaffected by the experiments, there should be no change in behavior to login services or embedded content.


The new SameSite rules will become the default behavior on Stable in Chrome 80, but the changes will be limited to pre-Stable versions of Chrome until then.


Policies to manage this behavior will be made available when it becomes the default behavior for Chrome 80. One policy will allow administrators to specify a list of domains on which cookies should be handled according to the legacy behavior, and second policy will provide the option to set the global default to legacy SameSite behavior for all cookies. More details about these policies will follow in future enterprise release notes before the Chrome 80 release.


Chrome continues to engage with members of the web community and welcomes input on these SameSite changes via our forum: https://groups.google.com/a/chromium.org/forum/#!forum/blink-dev