I just upgraded Rerng®IT with Drupal 4.6.5 and MySQL 4.1 to Drupal 5.7 and MySQL 5.0.32 on OpenFreeHost. The most classical problem is character set aka encoding. Drupal 4.6.5 still uses utf-8 on top of latin1 even though MySQL 4.1 supports utf-8. However, Drupal 5.7 will uses utf-8 on utf-8 natively if MySQL is 4.1 or later. So what is the best practice to upgrade Drupal through 3 major versions?