By default, the /opt/deeplearning/workspace directory is only writeable by the root user. Changing the direcotry's group to adm and making it writable for all users of that group will fix this. However, newly created directories by specific users will be writeable by its creator only: I sometimes log into my VM from a second laptop. In that a case, a directory created from my main laptop was not writable. Changing the umask to 002 fixed this issue.