Steam is down for many people, with launch error "loading user data" preventing a non-trivial group of users from playing games or accessing the store.
At the time of writing, SteamDB's status detector reports everything is in the green, but Down Detector shows ongoing reports of problems with Steam. Error reports began to spike around 8am ET today, October 26, and have continued to rise in the hours since.
Here in the Eastern US, I'm able to load Steam and boot a game without issue at the time of writing. However, one of my US coworkers ran into the "loading user data" endless loop just moments ago, and rebooting Steam multiple times didn't help resolve it.
If you're just looking to browse, make a purchase, or access social features, you may have better luck on the web version of the storefront, as this error seems to be on the launcher side.
Anecdotes that align with our experience suggest that redeeming a Steam product code or purchasing a game, then starting the download and installation process, could contribute to the "loading user data" stall. Valve has yet to comment on this reported issue.
This is the second Steam outage in a week, with the store briefly tanking on October 21 amid a storm of PHP vulnerability responses online. It's unclear if Valve was also reacting to PHP concerns, which saw newly discovered holes in a web-critical system potentially expose stores and sites to bad actors, or if the downtime was just strangely timed.
