Upgrading from Drupal 5.x

This is an extract from the Drupal 6 release announcement. If you are planning to upgrade from Drupal 5.x make sure you read this post carefully:

  • Ensure that you have Drupal 6 versions of all of your contributed modules and themes, and that you have reviewed and updated your site's custom code (if any).
  • When upgrading, always save backups of your original files and database.
  • Disable contributed themes and modules before starting the upgrade process. Contributed modules and themes may be upgraded after your core upgrade is complete.
  • Because some modules may have been renamed or removed within the Drupal core, you should not extract Drupal 6.0 on top of your existing installation. Instead, start with a fresh copy of Drupal and then add your custom modules, themes and configuration file.
  • If you are using the Update status contributed module for Drupal 5.x, you are encouraged to both disable and uninstall the module before upgrading to Drupal 6.0. Also, some of the advanced features of the contributed version of Update status were not moved into the Update status module included with Drupal core, and can be found in the Update status advanced settings contributed module for Drupal 6.x.
  • In Drupal 6, translation files are now spread across a set of small files, and distributed in a package (since importing translations from one large file did not work on some hosts). To import all new translation files automatically, uncompress the translation files into the Drupal root and use the Reimport tab (under Import page in the Translate interface administration section) provided by the contributed Localization client module. The Localization client module provides a number of useful features for managing and translating a multilingual site. Drupal 6 versions (when available) of other contributed modules, including i18n and localizer, also provide additional features that complement or complete the Drupal 6 multilingual feature set.

-- And please remember my upgrade mantra:
Backup, backup, backup! and then backup in a different format... and have somebody else backup on their side too.
Cheers and happy upgrading!