cant copy userfile out of docker

[simonbuehler]

when trying to issue the commadn to retreive the docker after automatic captcha run

$ docker run -it pikaptcha -p xxx -r xxx-c 10 -m x@xxx -t users.txt
i get this:
$ docker cp pikaptcha:/usr/src/app/users.txt . Error response from daemon: lstat /mnt/sda1/var/lib/docker/aufs/mnt/084f2d0f746f 3b27ab32d8b1996c703e724743be19dbcedc0223d3bd085feb43/usr/src/app/users.txt: no s uch file or directory

any idea?