Upon setting up a new WordPress site in a multisite configuration, I was hit by what appears to be a common problem vexing many a person: A fresh, new login page that replied to every administrator login attempt with “ERROR: Cookies are blocked or not supported by your browser“.
There are many examples of the problem, and many, many fixes (involving everything from refreshing the browser to editing the wp-config.php file or the selected theme’s functions.php file) detailed on the Internet. If you’ve hit the problem, do a Google search and start playing with the many solutions that come up. They work for many people – but you’ll also see many laments of “none of those work for me”.
That was my case, too. Here’s what ended up solving the problem:
In my WordPress database, the table w_domain_mapping contained rows for all sites in the multisite network, except for my new site. Why? I don’t know; it simply didn’t get created. I added a new row in the table and, following the example of existing rows, entered the new site domain, site_id (same for all sites), and blog_id (found in the w_blogs table, which did contain a proper row for the new site).
That did the trick. I was able to log into the new site installation and start building.
Anyone else find this to be a solution?