Can’t log in to wp-admin after setting up Multisite

Log into the admin area, then check the URLs in Settings, General. Those values should be similar to http://www.example.com .

The wp_options table in your database also has two entries for the site URLs. They should be the same as in Settings, General, but doesn’t hurt to check things. If you can’t login as admin, then check those two entries in the wp_options table for the correct URLs.

Then open a new, private browser window and login. (That reduces chance of your browser caching things.)