Here is the best way to update contributed modules on your Drupal 6 website:
1. Put your site into Site Maintenance mode. Go to Site Configuration>Site Maintenance and set your Site status to offline.
2. Flush the cache. Go to Site Configuration>Performance. Scroll down towards the bottom of the page and click on “Clear cached data” button. I recommend installing the module called "Admin menu". (
http://drupal.org/project/admin_menu) It places all the Drupal Admin functions in a menu bar at the top of your screen. You can easily clear the cache by clicking on the favicon on the upper left side of the menu and select "Flush all caches". As a Drupal developer, I end up clearing the cache a lot so having this shortcut is really helpful.
3. Backup all your site file. Backup your database using the Backup and Migrate module. (
http://drupal.org/project/backup_migrate)
4. To find out what modules need updating, go to Reports>Available updates. You will need to have this module enabled in Site Building>Modules. Look in “Core – optional” section and turn on the “Update status” module. Click Save.
Go to Reports>Available updates and see which modules need updating.
5. View the Available updates and scroll down to see what new updates are available.
Be sure to update to stable module releases that have a version number. Releases that say dev, alpha, beta or rc are not the most stable. Find the module you want to update and click on the Download button. Save the compressed file to sites/all/modules folder.
6. Delete the previous version of the module by deleting the folder and all its contents. Unzip the new module version.
7. Now you need to run update.php. You will see a message saying that you need to run update.php each time a module is updated. There is a link on the Site Building>Modules page for update.php. Click on this link. Or type in your web address bar: yourdomain.com/update.php
8. Follow the directions on the screen and view any errors logged. Most warnings can be ignored.
9. Go to Reports>Available updates, press refresh on your browser and see the new version info dispalyed. Check Status report. Go to the configuration page for this module and check the settings. You may need to adjust the settings and add new configuration. Test the module and make sure it’s working like expected.
10. If I have several modules to be updated, I usually update 2 modules at a time and make a database bakcup. If any critical errors have occurred after installing the new module, you will need to uninstall the module. Many modules do not have uninstall capability. In this case, you will need to restore your module to the previous version and also roll back your database to the previous version.
11. After you have finished updating your modules, put your site back online. Visit Site Configuration>Site maintenance and set your Site status to “online”.
Note 1: Some modules may require more time and attention. Then the developer usually includes more specific instructions in a README.txt or INSTALL.txt or UPGRADE.txt file. You can also view the "Project's page" on Drupal.org and click on links to read the release notes or any "Documentation" links
Note 2: Some modules can have additional files to download and/or customized settings stored in the module directory (CKeditor, for instance, has both). In that case, you will want to preserve the settings files, making sure they have not changed in format from the previous version, and copy the additional needed files.
