[Steam Flatpak] VAC server timeout occurs randomly in the middle of games

[saori-yuko]

Your system information

Operating System Version:
Freedesktop.org SDK 23.08 (Flatpak runtime) (64 bit)
Kernel Name: Linux
Kernel Version: 6.1.55
X Server Vendor: The X.Org Foundation
X Server Release: 12301002
X Window Manager: GNOME Shell
Steam Runtime Version: steam-runtime_0.20230801.56012

CPU Brand: Intel(R) Core(TM) i9-10940X CPU @ 3.30GHz
Driver: AMD AMD Radeon RX 6700 XT (navi22, LLVM 16.0.6, DRM 3.49, 6.1.55)

• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Expect results: I do not get disconnected from the game do to VAC timeout Actual results: I get disconnected from the game with VAC timeout

Steps for reproducing this issue:

1. Play CS2
2. Join an online game
3. Play for an hour or so

[saori-yuko]

This issue does not occur in the non-flatpak version of steam

"NixOS 23.05 (Stoat)" (64 bit)
Kernel Name: Linux
Kernel Version: 6.1.55
X Server Vendor: The X.Org Foundation
X Server Release: 12301002
X Window Manager: GNOME Shell
Steam Runtime Version: steam-runtime_0.20230801.56012

[benaryorg]

Same issue here, although it has been an issue for me since CS:GO days, and I can not test against a native version of Steam (since I don't trust Steam or the games enough to let it out of the sandbox).

Last time I ran a tcpdump in hopes of finding something and indeed shortly before the DC/timeout my computer sent almost three dozen duplicate Acks to let the remote server know that a single packet was dropped and needs to be resent, however the server just kept sending the regular TCP stream packets and did not provide the missing packet. After about 100ms of getting packets further down the stream and sending the dup-ack packets the timeout occurred. Looking at the initial TCP handshake and the TLS handshake on that connection it seems to me that the round-trip time seems to have been pretty much 100ms. So either this is a fluke, or even entirely unrelated traffic, or the VAC system is very sensitive to packet loss in this specific setup. That alone however would still not explain why this only happens in a Flatpak version of Steam.

I can provide the pcap if required.

[sawb]

This issue does not occur in the non-flatpak version of steam

"NixOS 23.05 (Stoat)" (64 bit)
Kernel Name: Linux
Kernel Version: 6.1.55
X Server Vendor: The X.Org Foundation
X Server Release: 12301002
X Window Manager: GNOME Shell
Steam Runtime Version: steam-runtime_0.20230801.56012

This issue frequently occurs on Non-flatpak steam for me.

[ech0devv]

Still having this issue w/ steam runtime

[g572staem]

Tangentially related, same symptoms. (NOT a duplicate, duplicate issues occur in the same time frame). https://github.com/ValveSoftware/steam-for-linux/issues/10920

( Ubuntu 20.04 LTS, Nvidia. OS does not have boffin nonsense going on, very vanilla install. )

[dzragon]

Same here, happens over and over. And have happened in Windows aswell. This time around though i had just Linux Mint 22, newest drivers for that system, and it just blurted out that message above on your screenshot.

Tried explaining to Valve support but they thought i was fishing for info about VAC so they havent helped at all. Just told me to come to GitHub and file a bug-report. Since im not a developer myself i have no use for an account on GitHub for anything except filing a bug-report, but seeing there already are others with the same thing, i can just beg to Valve: Please fix this.

Could it be that the problem also arises if the other team or other players on both teams report for cheat and that in turn makes VAC ask for a screenshot, and then it bugs out and cant provide it? Folder and file rights and so on? It wasnt like this in Steam on Linux a few years back. Even performance was above Windows fps wise back then. Now its back to lagging behind Windows again.

[Kishiko73]

Bug Encounters: 2025: Mar 28, Mar 14 (twice) 2024: Nov 23, Nov 13, and Sep 23.

System Information:

• Steam -> Help -> System Information: gist

• Steam Runtime Diagnostics: gist (I use steam-native from terminal to run steam, error also observed with steam-runtime)

• Have you checked for system updates?: Yes and no. On Mar 14 specifically, I had an outdated system for the first occurrence, then proceeded to update (sudo pacman -Syu) and verify game file integrity (also enabled secure boot in the BIOS - just realised) then I got timed out in my first game after restarting.

Launch Options (per occurrence): 1, 2: -sdlaudiodriver pulseaudio -console -fullscreen -nojoy -refresh 144 +fps_max 480 3: LD_PRELOAD="" %COMMAND% -console -fullscreen -nojoy -refresh 144 +fps_max 480 4, 5, 6: LD_PRELOAD="" %COMMAND% -console -fullscreen -nojoy +fps_max 240 -refresh 144 -w 1920 -h 1080

Speculative Info / Ramble (I don't have tcpdump to comment there): A lot of scenarios occur very quickly after a kill (200-1000~ms) usually with AWP/scout, then quick switching to unscope. But the most recent occurrence was while walk-swinging an angle where a CT exposed themselves without seeing me or me shooting them. It's not impossible it was triggered by the kill I got before that, but the delay was longer than usual, ~5s (Mar 28 timeout was also ~5s after a kill so maybe the delay was increased). The earlier kill was maybe a 300-500ms AWP shot on a player under B on vertigo, nothing particularly fast and a uniquely smooth flick for my usually shaky/snappy aim.

Regarding the player report speculation.. while I don't think it's related (having seen players copy paste their reports for me and not get timed out) this is what I can say about the 2 timeouts from Mar 14: Timeout # 1 was in the game on vertigo (10v10 lobby) after previously dropping around 20:2 on mirage and one player being very vocal about me "obviously cheating", later trying to vote kick me when we ended up on the same team. Timeout # 2 was a 1v1 lobby (5v5 w/ bots) that then turned into a 2v0 after a couple round wins on my end.