WordPress Multisite: cookies blocked or not supported

How to fix log-in error when using multisite

There are many support queries regarding the WordPress log-in error message: “ErrorCookies are blocked or not supported by your browser. You must enable cookies to use WordPress.” And there just as many possible solutions…

We found one case on multisite when using the new domain mapping feature that required an update to the wp-config.php file. You may find after mapping a custom domain to your multisite subdomain that it is no longer possible to get past this error message. In order to resolve this, add the following line to your wp-config file:

define('COOKIE_DOMAIN', false);

We’ve found that this seems to solve the problem.

5 thoughts on “WordPress Multisite: cookies blocked or not supported

Thanks for posting on this issue. However, when I add that to the wp-config.php file I get the following error across all sites:

The constant “COOKIE_DOMAIN” is defined (probably in wp-config.php). Please remove or comment out that define() line.

If you have any other fix for this I’d be grateful to hear it.


Do you have any other plugins that might be conflicting with this? For example, Domain Mapping?


thank you 🙂 .it worked for me by adding define(‘COOKIE_DOMAIN’, false)
wordpress 4.7


“ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.” just reared its ugly face with the installation/spinup of new subsite yesterday. I’ve tried your suggested fix and also added the following code to the bottom of the functions.php file: setcookie(TEST_COOKIE, ‘WP Cookie check’, 0, COOKIEPATH, COOKIE_DOMAIN);

Cleared browsers caches on several different browsers and on server and still I can’t log into that one new subsite. The other sites do not have the same problem just the new site.

Any ideas?


Wow, this is dumb: I forgot to add the new site to the Domain Mapping Configuration! That fixed it. Thanks and Happy Holidays!


Leave a Reply

Your email address will not be published. Required fields are marked *