Due to the number of versions available and recent changes in the configuration structure, specific upgrade instructions are not available. In general, the following steps should be taken:
Starting with version 2.04, backup and restore functions are available for mission critical upgrades. Use of these functions is highly recommended.
If you are experiencing problems with upgrading, uninstalling the program (from the Control Panel) before installing the new version should help.
In all cases, check through the server properties to make sure all your settings are still correct. Due to the many combinations of upgrade paths, some settings may contain garbage. All of your older settings should still be there.