protonscr

unity games won't start on some steam libraries

protonclosed
ValveSoftware/Proton#9938 · opened 2026-07-01 by ThomasSteve83 · updated 2026-07-02 · 7 comments · github
TThomasSteve83 2026-07-01 github

Your system information

  • Steam client version (build number or date): 1782437068
  • Distribution (e.g. Ubuntu): CachyOS x86_64
  • Opted into Steam client beta?: yes
  • Have you checked for system updates?: yes
  • Steam Logs: steam-logs.tar.gz
  • GPU: NVIDIA Geforce RTX 3050 [Discrete]

Please describe your issue in as much detail as possible:

i moved most of my games to a new library on a btrfs partition on a sata hdd, mounted at /mnt/ali-g

unity engine games running under proton, installed to this library, fail to start, referencing graphics drivers

Image

games installed to the library at ~/.local/share/Steam/steamapps/common/ work fine, as did games installed to a library on an ext4 partition on a usb hdd, mounted at /run/media/thomas/borat

changing mount permissions, tweaking compatibility settings, verifying and reinstalling games all yielded no different results

all my compatibility tools are installed at ~/.local/share/Steam/steamapps/common/ and ~/.local/share/Steam/compatibilitytools.d

Steps for reproducing this issue:

  1. create a library on an unlucky disk?
  2. install unity engine games that run under proton
  3. try to play said games
TThomasSteve83 2026-07-02 github

upon further testing, source and godot games now silently fail on ali-g
some software, such as ovr advanced settings (1009850) (running under proton) works fine

Kkisak-valve maintainer 2026-07-02 github

Hello @ThomasSteve83, can you check if there's a permissions issue with how the partition is mounted. (Perhaps noexec?)

TThomasSteve83 2026-07-02 github

Hello @ThomasSteve83, can you check if there's a permissions issue with how the partition is mounted. (Perhaps noexec?)

this was one of the first things i checked

$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a device; this may
# be used with UUID= as a more robust way to name devices that works even if
# disks are added and removed. See fstab(5).
#
# <file system>             <mount point>  <type>  <options>  <dump>  <pass>
UUID=75550685-4610-4239-8f2b-57b11504a1a2   /             ext4    noatime        0 1 
UUID=4234-01AC                              /boot/efi     vfat    umask=0077     0 2 
UUID=9976a321-7fbd-4ad8-8a45-a1b6aceddb09   /home         ext4    noatime        0 2 
UUID=07477fc4-23ed-4633-bb58-b4fdb7af7e2d   /mnt/ali-g/   btrfs   nofail,users   0 0

seems fine, as do the directory permissions

Kkisak-valve maintainer 2026-07-02 github

Please add PROTON_LOG=1 %command% to a couple game's launch options and attach the generated $HOME/steam-$APPID.log to this issue report as a file. (Proton logs compress well if needed.) Also, please copy the contents of Steam Runtime Diagnostics from Steam (Steam -> Help -> Steam Runtime Diagnostics) and put it in a gist, then include a link to the gist in this issue report.

TThomasSteve83 2026-07-02 github

i tried h3vr (450540) under proton hotfix and experimental, but the game never started at all and no logs were generated

tried the latest proton-ge as i had it on hand, and got steam-450540.log with the behaviors outlined earlier
i'm aware proton-ge isn't necessarily representative of proton in general

even when i thought this was more of a steam client issue, i should've mentioned i was generally using proton-ge, although i remember official versions acting the same at the time

and here's the runtime information

Kkisak-valve maintainer 2026-07-02 github

The noexec lines in the Proton log reenforces that there's a permissions issue with how the partition is mounted.

TThomasSteve83 2026-07-02 github

i overlooked some details of my system, the disk was mounted with noexec by default

Proton versions

Launch options