The TF2 Crate Depression: when a bug made every crate pay out

For one night in July 2019, the rarest items in Team Fortress 2 stopped being rare. A bug made some older crates give out an Unusual hat, normally a tiny fraction of openings, every time. Prices on the player market collapsed, trading was frozen, and the episode became known as the Crate Depression, a name Valve itself used in the title of its official update. It is still the clearest example of what happens when odds nobody publishes suddenly change.

How TF2 crates work

Valve added the Mann Co. Store to Team Fortress 2 in its Mann-Conomy update of 30 September 2010, along with crates as new items. Crates drop to players at random; opening one needs a key, bought from Valve or from other players. Each crate gives one item from its list, with a small chance of an Unusual: a hat with a particle effect such as flames. The game went free to play on 23 June 2011, and crates and keys stayed at the centre of its item economy.

Valve doesn't publish the odds. Players and the press have long put the Unusual chance at about 1% per crate, but that is a community estimate, not a figure from Valve.

What happened in July 2019

According to Valve, the bug was introduced on the evening of Thursday 25 July 2019 and let some older crates grant an Unusual hat on every opening. (Valve released a game update that day, adding the Summer 2019 Cosmetic Case; its post on the bug doesn't say which change caused it. Some press reports dated the bug to 26 July.) Word spread within hours. Demand for the affected crates shot up, players opened as many as they could, and Unusual hats flooded the Steam Community Market. Press at the time reported that trading sites switched off their automated Unusual services and that TF2 inventories were hidden on the Steam Community, which stopped trades and market listings.

Valve says it fixed the bug the following morning and trade-locked the hats from the bugged crates while it looked into what had happened. The chance of an Unusual from those crates had gone from about 1% to 100%, and the market value of Unusuals players already owned fell with it.

How Valve unwound it

Valve set out its decision in a post titled "Update on The Crate Depression of 2019" on 2 August 2019. It said its investigation found that a small number of accounts had acquired the bugged hats, and a smaller share of those had acquired a very large number of them. Its fix:

• The first bugged Unusual added to each account would be made tradable.
• Every other Unusual received because of the bug would stay permanently trade-locked.
• Bugged hats that players had deleted before the tradable date, worried they had done something wrong, would be restored under the same rules.
• Instead of keeping the trade-locked hats, owners could ask for a full refund on any number of them. Refunds would be the full price paid for any hats, crates or keys bought on the Steam Community Market or from the Mann Co. Store.

Valve said the hats being made tradable added up to about one month of Unusuals at the normal drop rate. On 16 August it updated the post: one Unusual per account had been made tradable, and affected players were sent to a Steam Support page to see which items were affected and request refunds. The post gives no deadline for refund requests. Valve said it had added safeguards to stop it happening again, but didn't say what they were.

Why it matters

Players could see the odds change in 2019 only because the change was huge. A smaller change, say from 1% to 0.8%, would have been invisible: there is no published figure to compare against. That is the case for publishers disclosing odds. Where a publisher does, as Valve did for CS:GO cases in China in 2017 (see Counter-Strike 2), or as the publishers in our drop-rate index do, players have a fixed number to hold the publisher to. In South Korea, a publisher that changed odds without saying so was fined: see the MapleStory cube case.

How we checked

Dates for the Mann-Conomy update and the move to free to play come from Valve's own announcements. The date of the bug, the name, the four steps, the refund terms and the mention of safeguards come from Valve's own post of 2 August 2019 (with its 16 August update), read on teamfortress.com on 4 October 2026 and again on 12 November 2026. We also read Valve's Steam news feed for the game from 25 July to 10 August 2019: it has no earlier Valve post about the bug, only the 25 July game update. The Steam Support refund page needs a Steam sign-in, so we couldn't read it. The market reaction (trading sites pausing, inventories hidden) comes from contemporary coverage by PCGamesN, Neowin and TechRaptor.