During these steps, we assume that the address of your blog is http://example.com/wordpress/.
Replace WordPress files
- Download the .zip file of the latest version.
- Unzip this archive to your computer.
- Disable your extensions.
- On the hosting server, delete the folders wp-includes and wp-admin through a FTP client or SSH access.
- Upload the entire contents of the archive (except wp-content), via a FTP client or SSH access, replacing the old files when it is needed.
ATTENTION: you must replace all the old files with the new WordPress files, including those located in the root of your installation, as index.php, wp-login.php and so on. Normally, simply copy the files over old is enough to replace them, but sometimes it is necessary to delete old files before you upload the new ones. Be very careful in this case, and follow the instructions. Only should remain intact customized wp-config.php file and the content of wp-content.
Be very careful with regard to the wp-content folder. Do not try to replace the files, just copy the new files, as this is the folder that stores your themes and extensions, you prefer certainly more keeping than losing it. Especially, if you changed the default themes without renaming it, make sure not to replace it – either by renaming or copying the file one by one.
Finally, open the wp-config-sample.php to see if new settings have been introduced there in the latest version, you would have to copy settings manually in your own wp-config.php
Delete file .maintenance
If you make a manual update after the failure of an automatic update, delete the file .maintenance from your WordPress directory using FTP. This will remove the impertinent message “failure of the update.”
Install your update
Once all the files are online, visit your administration dashboard, at /wp-admin. Perhaps you need to reconnect. If a database upgrade is necessary, WordPress will detect it and prompt you to click a link in the form http://example.com/wordpress/wp-admin/upgrade.php. Click it, and follow the instructions. Your database will be updated to run with the latest version. Make sure you follow this step as soon as possible after completing previous step.
Take a break!
If you have a cache system in place, empty it so that the changes appear faster for your users. You can check the cache returns the correct version with the version number displayed at the bottom of page.
It’s over! Congratulations! No easier, except to put in place a process using Subversion.
Write an article to announce your update, read a book or article that you keep for “when you have time,” or, simply enjoy these few minutes of free time available to you.
The update is complete, it’s time to re-enable your extensions. If you are having problems connecting, try to remove cookies from your browser.
If a problem occurs, the first thing to do is to restart the process by following the detailed instructions. They contain many tips and tricks to solve the most common problems.
If problems occur after the update, you can try to restore your database from a backup, and replace the files with those of your previous version, recovering the previous version of the site.
Translated from WordPress.org