Upgrading from XOOPS 2.0.* above 2.0.14 and 2.2.* (using the full package)
1. Move the "upgrade" folder inside the "htdocs" folder (it's been kept out as it's not needed for full installs) on your local machine
2. Delete htdocs/mainfile.php, htdocs/install/, htdocs/cache/, htdocs/extras/, htdocs/template_c/, htdocs/themes/ and htdocs/uploads/ from the "htdocs" folder on your LOCAL machine
3. Upload the content of the htdocs folder on your LOCAL machine over your existing files on your server
4. For security considerations, you are encouraged to move directories xoops_lib (for XOOPS libraries) and xoops_data (for XOOPS data) out of document root, or even change the folder names.
5. Make the directory of xoops_data/ writable; Create and make the directories of xoops_data/caches/, xoops_data/caches/xoops_cache/, xoops_data/caches/smarty_cache/ and xoops_data/caches/smarty_compile/ writable.
6. Ensure the server can write to mainfile.php
7. Access /upgrade/ with a browser, and follow the instructions
8. Follow the instructions to update your database
9. Write-protect mainfile.php again
10. Delete the upgrade folder from your server
11. Update the "system" module from the modules administration interface, other modules are recommended to update as well