Hi Wolfgang!

there is a decription how to update "my little forum" from version 1.7x to 2.2. But here still version 1.6.x is running. (BTW: Where do I find the exact version number?)

Well, in all 1.6x versions only the major revison (=not the x) is stored in the database. You can check that: Admin area > forum settings > advanced settings > version. I assume it will show "1.6" in your installation.
The first version saving the minor revision in the database was 1.7.4.

Can I use the same script dedicated to 1.7?

No, it will not work - lines 133... of the update script check the first three characters of the version number and will stop with an error message (and telling you the current version).

Do I have to update to 1.7 or make some special preparations first?

Yes. But don't be afraid (unless it's a very, very large forum - which may run into troubles with memory allocation and maximum runtime).

• Be sure that you still have the original forum.zip (I have 1.6.2 2006-03-07, 1.6.3 2006-06-18); they are not available at Alex' site anymore. If you don't have them, we can arrange something...
  
• Make a backup of the database (from within mlf1.6 Admin area > backup or restore database > complete SQL dump > wait until your browser reports finish, complete or something similar).
  
• Copypaste the entire browser's content to a text editor and save on your local machine.
  
• If you are familiar with phpMyAdmin, you may perform a backup there.
  
• Replace the forum's scripts on the server with version 1.7.6.
  
• Run install.php - the script will detect the database of v1.6x and will update the forum (no need to restore the database!).

I started with 1.4.1β and ended up with a heavily patched 1.7.6 without problems in any of the updates in between.

Now for the worst case: The update 1.6x > 1.7.6 fails. Oops. Replace the 1.7.6 scripts with the old 1.6x ones, run install and restore the backup database.

Servus aus Wien.