New Steam runtime: Proton 5.13-1 breaks in Silverblue (bwrap: Can't mkdir /usr/lib64/gconv: Read-only file system)

The new proton release and Steam runtime (soldier) break on every game start via Steam with the following log in Silverblue:

bwrap: Can't mkdir /usr/lib64/gconv: Read-only file system
ln: failed to create symbolic link '/run/user/1000/SteamLinuxRuntime.4297668b2bb5059a/socket' -> '': No such file or directory

I’ve not found a workaround except disabling the runtime yet.

EDIT: Still debugging the issue. Maybe this is not the root cause.

Available workaround: https://github.com/flightlessmango/MangoHud/issues/369#issuecomment-709902078

use flatpak steam, not rebase system

The flatpak steam has limitations which make it not an alternative for me as of now. The new Steam runtime is not able to run inside flatpak (https://github.com/ValveSoftware/Proton/issues/4283) (yet) and SECCOMP is not supported in flatpak which breaks some Denuvo games (https://github.com/flathub/com.valvesoftware.Steam/issues/608). I’ll continue to keep an eye on it.

The new runtime is not a runtime, but a container solution similar to flatpak in some regards. Not compatible in the meantime.

just need to be patient, as always.