Traceback (most recent call last):
  File "/usr/lib/hplip/ui/devmgr4.py", line 1828, in PrintTestPageButton_clicked
    d.open()
  File "/usr/lib/hplip/base/device.py", line 974, in open
    raise Error(ERROR_DEVICE_NOT_FOUND)
Error: ('Device not found', 2)