Multisite Cookies are Blocked Login Error

Have you ever set up a multisite network, started working on setting up a new subsite, and then get the cookies are blocked login error?

I have, and it really didn’t make any sense.

The first thing I looked for was my browser’s cookies settings. First, I made sure cookies were enabled. Then I checked that cookies weren’t blocked on the site I was trying to log into.

How to check if cookies are enabled

Each browser is a little different, so I’ll break it out by some of the more common browsers.

Chrome

• Click the three dots at the top right side of your address bar.
• Select Settings.
• Scroll to the bottom and click Show advanced settings…
• Under Privacy, click the Content settings… button.
• Make sure the button next to Allow local data to be set (recommended) is selected.
• Make sure the check box next to Block third-party cookies and site data is not checked
• Next, click the Manage exceptions… button.
• Make sure the site you are trying to log into is not listed with a Block behavior.
• Then, click Done on both windows and close the settings.

Firefox

• Click the hamburger menu (three horizontal lines) to the right of the address and search bar.
• Select Options.
• Select the Privacy tab on the left.
• Under History, select Use custom settings for history under the Firefox will menu.
• Check the box next to Accept cookies from sites.
• Set Accept third-party cookies to Always.
• Set Keep until to they expire.
• Next, click on the Exceptions button.
• Make sure the site you are trying to log into is not listed with a Block status.
• Click the Save Changes button.
• Then, close your options tab.

Safari

• Select Safari, then Preferences, then click Privacy.
• Under Cookies and website data, select Always allow.
• Then, close the preferences screen.

For me, none of those settings fixed the problem. I was able to log into other WordPress sites with no problem, so cookies were enabled.

Cookie settings in wp-config.php

The fix for me came in adding a few lines to my multisite’s wp-config.php file.

<?php
//Do not include the opening <?php tag
//Place the following four lines somewhere before the "That's all, stop editing! Happy blogging." line
define('ADMIN_COOKIE_PATH', '/');
define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');

You may need to close your browser and try logging in again, but after that, you should be able to log in.