Why QDir::exists() do not work in docker container?
I got the answer from apachelogger on KDE forums:
Since 5.10 Qt is using somewhat new syscalls. One of them is statx and last I checked the syscall was not whitelisted in docker, nor was it whitelistable because the libseccomp used for the upstream docker build was too old and didn't know what statx is. Chances are the problem you see is that. If so, seccomp=unconfined would make it work.