I decided to integrate several standalone WordPress websites into a single Multisite installation.
I created a brand new Multisite install with subdomains, created a MU network site with subdomain URL, and exported the content from the original standalone site, then imported that content into the subdomain MU site. I then deleted the original standalone site from cPanel, and set the MU site's domain name to the original domain name.
The main site loads fine now on its original domain name, but when I try to login to the subdomain site at
site.example.com/wp-admin/ (using the brand new multisite's network admin user credentials), I receive an error:
ERROR: Cookies are blocked or not supported by your browser. You must enable cookies to use WordPress.
But cookies are enabled in Chrome.
I tried adding the following to
...but the issue remains.
The same issue occurs if I use WP Migrate DB Pro to pull in a standalone website into a MU subdomain site, then delete the standalone site from cPanel, and then set the MU subdomain site's domain to be the original standalone site's domain name... the site's frontend loads fine, but I just can't login to WP admin.