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SameSite Updates

Launch Timeline

Last updated March 9, 2020.


We have begun enforcing the new behavior for Chrome 80 stable, just not for 100% of users. The controlled rollout is to a limited initial population, and the proportion of users receiving the new behavior will be gradually increased until it reaches 100%. This is standard procedure for features with large, potentially disruptive impact.


For the full Chrome release schedule, see here. For the SameSite-by-default and SameSite=None-requires-Secure launch timeline, see below:

  • 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.
  • Dec 10, 2019: Chrome 79 Stable released. Stable users on Chrome 79 will NOT receive the new SameSite behavior.
  • Dec 19, 2019: Chrome 80 Beta released. Experimental behavior still enabled for 50% of Chrome 80 Beta users.
  • February 4, 2020: Chrome 80 Stable released. The enablement of the SameSite-by-default and SameSite=None-requires-Secure enforcement will not be included in this initial Chrome 80 stable rollout. Please see the next item for more detailed information on the when SameSite enforcement will be enabled for Chrome 80 stable.
  • February, 2020Enforcement rollout for Chrome 80 Stable: The SameSite-by-default and SameSite=None-requires-Secure behaviors will begin rolling out to Chrome 80 Stable for an initial limited population starting the week of February 17, 2020, excluding the US President’s Day holiday on Monday. We will be closely monitoring and evaluating ecosystem impact from this initial limited phase through gradually increasing rollouts. 
  • March 2, 2020The enablement of the SameSite enforcements has been increased beyond the initial population. However, it is still targeting an overall limited global population of users on Chrome 80 stable and newer. We continue to monitor metrics and ecosystem feedback via our tracking bug, and other support channels.
  • March 9, 2020The rollout population has been additionally increased, although it continues to target a fraction of the overall Chrome 80 stable population. We continue to monitor metrics and ecosystem feedback via our tracking bug, and other support channels.
More specifically (as of March 2, 2020), if you are currently using
  • Chrome 79 and older: Your Chrome version is out of date! Please update Chrome to the latest Stable or pre-Stable version for the most up-to-date cookie behavior as well as security/stability/speed improvements.
  • Chrome 80: The new SameSite behavior is being rolled out to Chrome 80 Stable users through gradually increasing rollouts, as described in the timeline above. 
  • Chrome 81-82: There is a 50% chance that the new SameSite rules are active in your browser, ONLY if you are using Chrome Canary, Dev, or Beta. Chrome 81-82 Stable have not yet been released. The SameSite behavior will be gradually rolled out to an increasing proportion of Chrome 81-82 Canary/Dev/Beta users along with the increasing proportion of Chrome 80 Stable users.
The new SameSite behavior will not be enforced on Android WebView until later, though app developers are advised to declare the appropriate SameSite cookie settings for Android WebViews based on versions of Chrome that are compatible with the None value, both for cookies accessed via HTTP(S) headers and via Android WebView's CookieManager API. This does not apply to Chrome browser on Android, which will begin to enforce the new SameSite rules at the same time as the desktop versions of Chrome. The new SameSite behavior will not affect Chrome on iOS.


Latest update: Feb 10, 2020

All updates:


Feb 10, 2020
The Chrome policies LegacySameSiteCookieBehaviorEnabledForDomainList and LegacySameSiteCookieBehaviorEnabled which revert to the legacy cookie behavior for managed Chrome and ChromeOS instances will be available for at least 12 months after the release of Chrome 80 stable. We will be monitoring feedback about these policies and will provide updates on their lifetime as appropriate. 


Nov 21, 2019

Starting in Canary version 80.0.3975.0, the Lax+POST temporary mitigation can be disabled for testing purposes using the new flag --enable-features=SameSiteDefaultChecksMethodRigorously to allow testing of sites and services in the eventual end state of the feature where the mitigation has been removed. (Note that to enable multiple features, you must append the feature name to the comma-separated list of params for the --enable-features flag. Do not use multiple separate --enable-features flags.)

In addition, there is a bug affecting Chrome 78-79 which causes spurious SameSite warning messages to be emitted to the console when the user has cookies for other domains on the same site as a resource fetched in a cross-site context. We apologize for the confusion. This will be fixed in Chrome 80.


Nov 1, 2019

Clearing up some misconceptions and providing additional information about "Lax + POST" (which is mentioned briefly on the chromestatus.com page):
  • "Lax + POST" does not result in the legacy behavior (i.e. the old behavior before the SameSite changes).
  • “Lax + POST” is an intervention for Lax-by-default cookies (cookies that don’t specify a `SameSite` attribute) which allows these cookies to be sent on top-level cross-site POST requests if they are at most 2 minutes old. “Normal” Lax cookies are not sent on cross-site POST requests (or any other cross-site requests with a non-idempotent HTTP method such as PUT). This intervention was put in place to mitigate breakage to some POST-based login flows.
  • If “Lax + POST” is affecting the cookies you are testing (i.e. if your cookie would have been excluded if not for the "+ POST" behavior due to its age), you will see a message in the DevTools console about the 2 minute threshold. This can be useful for debugging.
  • For integration testing (if your cookie needs to be sent on cross-site POST requests), we recommend test cases with cookie age both below and above the threshold. For this, there is a command-line flag --enable-features=ShortLaxAllowUnsafeThreshold, which will lower the 2 minute threshold to 10 seconds, so that your test doesn’t have to wait for 2 whole minutes. This flag is available in Chrome 79.0.3945.16 and newer. (Note that if you are also using other --enable-features flags such as --enable-features=SameSiteByDefaultCookies,CookiesWithoutSameSiteMustBeSecure, you must append the feature name to the comma-separated list rather than use multiple --enable-features flags.)
  • 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 old.

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


Note (Jan 30, 2020): Check out our more detailed tips for testing and debugging.


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