At first, I brought some codes which are related the error I had.

status = recvmsg(fd, &msg, 0);
h = (struct nlmsghdr *)buf;
if(h->nlmsg_type == NLMSG_ERROR)
{
struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
errno = -err->error;
printf("errno = %s \n", strerror(errno));
}

After receiving packets through recvmsg, nlmsg_type was NLMSG_ERROR
which is the case above in if condition.
And errno which is printed above, was "File Exists".

I don't understand this two things. Especially, what does this "File
Exists" means while using netlink?

Hope to hear some recommendation.
Thanks in advance.