Where are the categories in my Steam library saved? Can I recover them if Steam forgets them?

Solution 1:

The categories are stored in the file $STEAM/userdata/$UID/7/remote/sharedconfig.vdf, where $STEAM is the Steam install directory and $UID is your numeric Steam user ID. If you're the only person who uses that install, there'll only be one directory in userdata/, so it's easy enough to find.

In principle, this file should be synced to the Steam cloud and every Steam client you log into. In practice, Steam seems to misplace it sometimes, or roll it back to an earlier version unexpectedly. Backing it up and restoring it when your categories go away should restore the categories as they were when you backed it up - don't restore it while Steam is running.

Anecdotally, explicitly exiting Steam after making category changes (as opposed to logging in from another machine or letting it run until the next power outage) has a high success rate of not losing my category changes, but I don't know what the actual cause is.