Is it possible to upgrade Drupal from very old version(4) to the newest one(7)?

I have to upgrade website running very old version of Drupal (cannot even find out which version is that, but I guess it is even before 5) to the newest one? Is th开发者_开发技巧at possible? If yes, how to approach this?

The Drupal web site makes it clear that you cannot skip major versions when doing version upgrades.

See this page: http://drupal.org/upgrade/

(it talks about not being able to skip from v5 to v7; it doesn't even mention v4!)

So if you do manage to upgrade your site all the way from v4.x to v7, one thing is for certain - it's going to be a long-winded process.

The other thing that is going to be a major issue for you is that the Drupal module ecosystem has changed radically in the space of time between v4.x and v7. Many modules that you'll be using in v4 will be either unsupported in later versions, or not have an upgrade path, so you may have a lot of manual hacking to do.

On the flip side, there are likely to be newer modules that can do things in recent versions of Drupal which were not possible in older version or were done in a very different way, and you may find yourself wanting to use some of those modules instead of ones you've got in place. Again, lots of manual work I forsee for you.

In summary, I would suggest that upgrading from such a long way back to the current version is going to be extremely difficult. You may find it easier to start again from scratch and rebuild everything. I'm sure you could get some data imported from the old site to maintain continuity.

One further thing I would add is that this isn't a Drupal-specific problem, so please don't blame the Drupal developers if you struggle with this upgrade - you'll get this issue with virtually any software you run if you don't keep it up-to-date. Try upgrading a Windows95 machine to Windows Vista and you'll see what I mean.

It would be possible, but could be very hard.

You would need to go from 4 to 5, then 5 to 6, and finally 6 to 7. You will have to make sure that your data is still intact along each upgrade and back up your database. Update any contributed modules and check if any have been deprecated along the way and find suitable replacements if possible.

Depending on your site, if it is just the content and you are not concerned with losing url aliases, taxonomy terms, etc. then trying to export/import your raw data directly into a fresh drupal 7 install might be easier.

Edit: You would also need to upgrade any custom themes and modules drastically.

I do not envy your task, as you will need to learn the changes from D4 to D5 only to later discard this knowledge as you learn the changes to become D6 compatible and then discard that knowledge to become D7 compatible.

As you said you do not really care about losing taxonomy terms or extras, you might want to try http://drupal.org/project/import_html or a similar module to scrape your website (though it is not actually static) and convert it automagically into nodes. That module is not currently available in D7, but would get you from D4 to D6.

The key thing to remember is frequently backup your database in case anything goes wrong or you want to try different upgrade paths.

It is doubtful that many contributed modules you are using would survive the upgrade, unless there is a release for each of versions 4, 5, 6, and 7. I agree with @brian_d, the best course of action may be to export your content and import into a fresh Drupal 7 site.

The general procedure for updating:

Assuming you are on version 4.7.x of Drupal:

1. Update Drupal and any contributed modules you can to the latest release for 4.7.x, in case there were schema changes
2. Disable contributed modules
3. Update Drupal to the latest version of 5.x
4. Update and re-enable modules/themes to the latest release for 5.x
5. Repeat steps 2-4 for 5.x to 6.x and again for 6.x to 7.x

I've been using Drupal since 4.x. During that time I've had to upgrade numerous times. Mostly I've had good success using the standard upgrade process. However, I've had to do several upgrades manually because of one issue or another. This was basically a Copy and Paste upgrade.

To read more about the Copy and Paste Upgrade go here: Upgrading Drupal by Copy and Paste.