Can you still reproduce this with the latest version of upstream QEMU? Please also provide the exact steps (e.g. command line options) that you were using here.
** Changed in: qemu Status: New => Incomplete -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1542965 Title: Failed to set NBD socket ubuntu 15.10 & nbd client 3.10 Status in QEMU: Incomplete Bug description: Running command to mount using nbd fails with error /build/qemu-YZq7uh/qemu-2.3+dfsg/nbd.c:nbd_init():L670: Failed to set NBD socket To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1542965/+subscriptions