Switching from Subversion back to general release or downgrading
From SqueezeboxWiki
Note that SlimServer saves stateful informaiton about server and player settings in a text file. Generally speaking, when you install a Subversion checkout or a newer version of SlimServer, it may "upgrade" portions of this file. For instance, the top-level player menus changed after SlimServer version 5.3.x. This is a good thing – unless you switch back to a non-Subversion or otherwise "earlier" release of SlimServer, which might become confused.
For example, on Linux the stateful preferences are stored in a file named .slimserver.pref in the home directory of the user running the SlimServer software, or in /etc/slimserver.pref. The /etc/slimserver.pref file is used if it exists. On MacOS X, the preferred location is
Home->Library->SlimDevices->slimserver.pref; on Windows,C:\Program Files\SlimServer\server\slimserver.pref.
When a user shuts down SlimServer 5.3.1 and then runs a pre-5.4 version from Subversion, the Subversion version changed the menu settings for the players in ~/.slimserver.pref so that SlimServer would offer the new menu hierarchy to the players. If the user subsequently shut down the CVS version and restarted the 5.3.1 release, SlimServer sees the new menu listings from the changes made to ~/.slimserver.pref by the CVS version. Most of the menu items display & work properly, but some do not. One menu item shows as an empty line with the "->" right arrow on the player... and clicking the right arrow when this is displayed crashes SlimServer 5.3.1.
For that reason, you may wish to save a copy of slimserver.pref before switching SlimServer versions in case you decide to revert. A simple copy would do fine, though programs like GNU RCS offer advantages over simple copying.
As of SlimServer version 6.5, much information is stored in a MySQL database. This database uses binary files in SlimServer's Cache directory, so you will also want to be careful to back up the Cache directory. More information on this and such things as running different versions of SlimServer 6.5 or newer on the same machine can be found in the forums: http://forums.slimdevices.com/showthread.php?t=34246