Upgrading from any XOOPS ranging from 2.0.7 to 2.0.13.2 (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)
2. Delete htdocs/mainfile.php, and htdocs/install
3. Upload the content of the htdocs folder over your existing files
4. Delete the following folders and files from your server (they belong to an old version):
* class/smarty/core
* class/smarty/plugins/resource.db.php
5. Empty the templates_c folder (except index.html)
6. Ensure the server can write to mainfile.php
7. Access <your.site.url>/upgrade/ using your browser, and follow the instructions
8. Write-protect mainfile.php again
9. Remove the upgrade folder after use
10. Update the "system" module from the modules administration interface