I can't log in to the administrator, the page just reloads

Why it happens

You type the right password, the page reloads, and you are still on the login form: Joomla didn't get to keep your session. The login cookie was rejected, or the session couldn't be stored.

Fix it, step by step

1. Clear the site's cookies in your browser, or try a private window.
2. In configuration.php, set cookie_domain and cookie_path to empty, and live_site to empty.
3. Check force_ssl: if it forces HTTPS but your site has no working certificate (or the reverse), logins fail.
4. In phpMyAdmin, empty the #__session table.
5. Check tmp_path points to an existing, writable folder, and the disk isn't full.
6. If it started after installing a plugin (especially an authentication or security plugin), disable it in the #__extensions table.

Good to know

• A wrong password shows a message ("Username and password do not match"). A silent reload is almost always cookies or sessions.