Here are the instructions for upgrading your WordPress installation manually.

1. Download and extract the WordPress upgrade to your hard drive.
2. If plugins are important to you, make sure your plugins are compatible with the version of WordPress that you are upgrading to. You can do this be searching Google on WordPress and the name of the plugin.
3. Backup your database. You can do this through cpanel or via the WordPress databases backup plugin.
4. Test the backup. It should look like a big text file of running together gibberish. If you do not have that, then stop the upgrade
5. Backup your WordPress files – all of them. Backup the wp-admin, wp-content, wp-includes, and all of the files in your blog directory. You can do this via cpanel or via ftp. I use ftp and copy them all all to my hard drive so I have them while upgrading.
6. Test the backup. Spot check and make sure the files are there – especially wp-config.php and your wp-content folder.
7. Install and activate the Maintenance Mode plugin. One note here – if you are backing up from a much older version of WordPress, skip this step. I find it can cause unnecessary problems and it’s better for your site to simply be down temporarily then to have to struggle to bring it backup later.
8. Deactivate ALL of your plugins, except for Maintenance Mode. Please do not skip this step
9. Logout of WordPress
10. Ok – back to FTP or your cpanel file manager.
11. Delete WP-Admin – yes, the entire folder
12. Delete WP-Includes – if you have language files, keep those. I have not upgraded a site that had them so most of you are safe in deleting the entire folder. And remember, we already made backups.
13. Delete all of the files in the blog directory such as wp-cron.php, wp-login.php, etc except for wp-config.php (that contains your database information). But if you get delete happy, you already have a backup.
14. DO NOT delete wp-content. Some upgrade instructions say to keep some of the files but not all of them. 98% of the time leaving that directory alone is just fine.
15. Now we are ready to upload the new WordPress files
16. Upload the wp-admin directory
17. Upload the wp-includes directory
18. Upload the main blog directory files such as wp-cron.php and wp-login.php The upgrade files should not have wp-config.php but, if it does, do not overwrite yours.
19. In your web browser, go to your site https://www.yoursite.com/blog/wp-admin/upgrade.php
20. You may be asked to login. Login.
21. If it was more than a .1 version upgrade, you may get a message saying your database needs to be upgraded. Click the button and upgrade.
22. Activate and upgrade your plugins.
23. If all is well, you are done and are now enjoying your freshly upgraded WordPress

A couple of issues that I have run into have been the following:

1. Can not login after upgrade. Clear your cache. Clear your cookies. If you still can not login, delete the plugins folder. You have a backup so they can easily be replaced. This is in wp-content / plugins /. Those three methods have always corrected this problem for me. If you still can not login, search the codex or contact someone like me for assistance.
2. Main page loads but get 404 errors on all sub pages. This is probably a permalinks problem. Delete your .htaccess file and replace it with the backup.

Out of all the upgrades I have done for myself and for others those are the only problems that I have encountered. So, I trust my system. If you still do not feel comfortable upgrading, ask someone for assistance.

Source by Kim Woodbridge