I have a Zebra GC420d thermal printer connected via USB to my Windows 7 Pro workstation, which I recently upgraded from XP.

On first connection, Windows automatically installed a ZDesigner driver that uses the old EPL printing language. That driver I assume was left over from Windows XP, since it happened right away.

Printer works, test page prints.

I want to use a driver that uses the newer ZPL printing language, either by ZDesigner or Seagull Scientific. Upon installation, a test page from a device using either of these drivers prints. Windows lists the print within the same icon under Devices and Printers (combining because they both use the Virtual USB port, apparently).

If I then uninstall the original EPL Printer Device, test page from new driver still prints.

However as soon as I reboot the machine or printer, Windows will immediately install the original ZDesigner EPL driver.

I have used the Print Server section under Computer Management to uninstall all printer devices and uninstall all the driver packages. I then re-install one of the ZPL drivers and add a printer using it. So there is only one printer showing under Devices. At this point the test page does not print.

If I power cycle the printer, ZDesigner EPL is installed again (even though I supposedly removed it entirely in previous step). Now there are two Printer devices, and test pages from either one works.

If I edited the Advanced Options of the Printer that uses "ZDesigner EPL" and manually change the driver that it uses, test pages will no longer print.

Any advice? I'm tearing my hair out on this. Right now things are working 'okay' with both drivers installed, but it is hard to diagnose some issues and I'd like to be able to know for sure which driver is responsible for printing. I really just want to be rid of the old driver entirely and have it work with the new driver.


I've encountered this exact problem in our environment, and it was problematic because we are using ZPL configurations which were getting over-ridden by the EPL driver (specifically, we wanted to use printer settings saved on the devices, instead of settings from the host drivers).

As stated on this zebra help page ZebraDesigner Driver Unspecified or Unknown Device Error or Not Communicating with Windows 7 and Windows 8,

The “Unspecified” driver that the Windows OS associates the Zebra printer with is a USB port that it automatically chooses. Since this port has no association to a ZebraDesigner driver it does not know how to communicate with the Zebra printer.

Essentially, regardless of the fact that, for example, you installed the NON-EPL version of the driver (either manually, or via Zebra setup tools), windows may detect its own instance of the device and default to the EPL version.

Easiest way to circumvent this is to:

  • remove all devices that are associated with your printer (from Devices and Printers, right-click the device and choose "Remove device"). (you may need to unplug the printer first).

  • Reboot the system and reconnect the USB cable.

  • Open Devices and Printers, locate the EPL version of the device which was installed. Print a test page to confirm that the proper device is being targeted.

  • Manually change the EPL driver to the NON-EPL driver, as instructed on Technet Update and Manage Printer Drivers

To update or change printer drivers for a printer Open Print Management. In the left pane, click Print Servers, click the applicable print server, and then click Printers. In the center pane, right-click the printer with the driver that you want to change or update, and then click Properties. Click the Advanced tab. Select a new driver from the Driver box, or click New Driver to install a new printer driver.

Note: You must do this replacement via Administrative Tools > Print Management. Doing a switch via the Printer properties may not give the same result. For completion, reboot the system and verify that only a single instance of the device now exists.

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