Upgrading from one Drupal release to another is what you call a nontrivial task. As such, you really need to follow in the footsteps of those who are more experienced and can show you the pitfalls and possible problems you may encounter. For this reason, before even describing the basic steps, a recommended reading list is presented at the beginning, rather than at the end of this chapter.
Then the basic steps are outlined, and then you are taken by the hand and led through the complete detailed procedure you can later put to use yourself, using a real-world example, my blog,
http://awebfactory.com.ar. It has been running for about three years now on Drupal, since October 2005. It started out on Drupal 4.4 or so. On the blog, there is an article on how I upgraded from Drupal 4.7 to Drupal 5.x ("Updating awebfactory.com.ar from 4.7 to Drupal 5";
There is even a before-and-after thumbnail, because I changed over to a custom theme. This time, however, I will be more than satisfied if I can get the same theme working as is under Drupal 6.x
So, here we go.
The more you know, the better! Before upgrading, study the following references:
Drupal Handbook upgrade pages:
The UPGRADE.txt file found in the document root of the Drupal 6.x file tree is by all accounts the best (if not only) reference material; as well as the documentation that comes with each Drupal module.
Greg Knaddison ...