SteamOS 3.9.3 can stop an encrypted Steam Deck booting, and Valve's only reply was a link
A Steam Deck with an encrypted home partition stopped booting after its owner installed the SteamOS 3.9.3 beta, and an instruction not to install that build on an encrypted machine had been sitting on Valve's tracker for more than a day. The report, filed on October 19 at 00:36 UTC, says the screen that asks for the password to unlock the partition "only flashes on screen briefly before going to a black screen that does not respond to input".
The third of five screenshots on Valve's own Steam store page for the Steam Controller. Image: Valve
Valve answered in nine minutes, and its answer was a link. The kisak-valve account, which is the one that posts as Valve on these trackers, replied with a single line pointing the owner at a comment on a separate thread about disk encryption.
The warning in that comment is not Valve's. Alberto Garcia, the developer who answers for dirlock on that thread and whose GitHub profile gives his organisation as Igalia, posted it on October 17: "if you're using dirlock don't install SteamOS 3.9.3 (20261015.100) from the beta / preview channels, there's a regression that could prevent the system from booting. It'll be fixed in the next update". The promise of a fix is his, with no version number and no date attached to it, and Valve has not repeated it anywhere.
dirlock encrypts the Deck's home directory, and the unlock screen is where it fails
dirlock is the tool SteamOS uses to encrypt a Deck's home directory, and Valve hosts its documentation on its own GitLab. With it switched on, the password that unlocks the partition is typed at the login screen on every boot, and that is the screen that goes dark here.
The build is SteamOS 3.9.3, which Valve published to the beta and preview channels on October 16, and the warning names its BUILD_ID as 20261015.100. Anyone on stable SteamOS 3.8 is untouched. Valve's notes for the build flag a single known issue, about which WiFi backend an existing installation keeps, and say nothing about dirlock, encryption or booting. The same build is the one that puts back the Android binder option owners say Waydroid needs.
Valve Index as shown on its own Steam store page. Image: Valve
Reverting to 3.9.2 brought the machine back
The owner says the Deck came back after a revert to 3.9.2, and that the 3.9.3 update was applied twice, "both times to the same effect", which the report takes as evidence that the fault is in 3.9.3 rather than in one bad installation. Connecting an external display did not bring the login screen back either.
A second owner described the same failure on October 17, with the unlock screen producing no display output, and got back into the machine over SSH instead. That is one recovery on one machine rather than a supported route.
It is the third dirlock fault reported in under a month. Garcia told owners on September 24 not to enable dirlock on SteamOS 3.9 at all, because of a kernel bug that crashed the system, while adding that anyone who had enabled it earlier would not hit that crash. Four days later he traced another report, from an owner whose Deck would no longer go into Game Mode, to the ownership of a dirlock configuration file.
The second screenshot on Valve's own Steam store page for Half-Life: Alyx. Image: Valve
Steam Frame has no dirlock yet, and no date for it
An owner noted on October 7 that dirlock "appears to be missing entirely from the Steam Frame so far", and Garcia answered on October 15 that the headset "is currently using a different build of the OS" and that "it will be included in the future". No version and no date are attached to that either, and the Frame is on a separate release line that stood at 0.5.6 on its beta channel on October 16.
The 3.9.3 beta has a second open complaint, filed on October 19 by a Steam Machine owner whose update hangs at about 95%, with the post-install step waiting on a filesystem it had just frozen. It has no reply.
Valve has published no known-issues note and no fix date for the boot failure, and the encryption thread has been quiet since October 17. For an encrypted Deck the practical position is still the one Garcia wrote: stay off 3.9.3.
