\Debugger entered--Lisp error: (file-error "Setting ACL" "Operation not permitted" "/mnt/Data/ActiveFiles/thuis~")
  set-file-acl("/mnt/Data/ActiveFiles/thuis~" "user::rwx\ngroup::rwx\nother::rwx\n")
  set-file-extended-attributes("/mnt/Data/ActiveFiles/thuis~" ((acl . "user::rwx\ngroup::rwx\nother::rwx\n") (selinux-context nil nil nil nil)))
  backup-buffer-copy("/mnt/Data/ActiveFiles/thuis" "/mnt/Data/ActiveFiles/thuis~" 511 ((acl . "user::rwx\ngroup::rwx\nother::rwx\n") (selinux-context nil nil nil nil)))
  backup-buffer()
  basic-save-buffer-2()
  basic-save-buffer-1()
  basic-save-buffer(t)
  save-buffer(1)
  funcall-interactively(save-buffer 1)
  call-interactively(save-buffer nil nil)
  command-execute(save-buffer)