A Zebra GK420d that skips labels, feeds blanks, or prints one label and stops is almost never broken hardware. Three things fix the vast majority of cases: (1) recalibrate — with the printer ready, hold the FEED button until it feeds a couple of labels and the light blinks (the GK420d has no SmartCal, so this FEED-button calibration is the equivalent); (2) set Media Type to Web Sensing / Gap for die-cut labels in the ZDesigner driver; and (3) match the driver label size to your media exactly. If it prints garbage, check the EPL vs ZPL language. On Windows 11 a wrong or generic driver is usually the root cause.
You send a job to your Zebra GK420d and it either does nothing, spits out a blank label, feeds two or three labels for one print, prints a single label and stops, or spews strange characters. You've reloaded the roll, power-cycled the printer, maybe reinstalled the driver — and it keeps happening. This is one of the most common GK420d complaints, and the good news is that it's almost always a calibration, media-type, printer-language, or driver problem, not a dead printer.
The GK420d is an older but extremely common direct-thermal desktop printer. It finds the edge of each label with a media sensor, and it understands two printer languages, EPL and ZPL — shipping in EPL mode by default. When it "skips" labels or feeds blanks, it has lost track of where one label ends and the next begins, so it overshoots or prints in the wrong place. When it prints garbage, the command language is mismatched. The fix is to re-teach it the label geometry (calibration), tell Windows the right label size and media type (driver), and keep the language consistent. Let's go in order, fastest fix first.
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Symptoms: What This Looks Like
- Printer feeds one or more blank labels for every print job
- Skips every other label — prints one, feeds past the next
- Prints one label and stops, ignoring the rest of the job
- Content is shifted up or down, or spills across the gap onto two labels
- Printer spits out garbage characters or blank pages full of text-like symbols
- Print is faded or light, or only part of the label prints
- The status light blinks red or the printer pauses mid-roll
- It worked fine, then broke after a Windows update or after changing label size
Fix 1: Recalibrate With the FEED Button (Start Here)
Calibration teaches the GK420d the exact length of your labels and the size of the gap between them. Any time you change label size, switch rolls, or start seeing skipping, this is the first thing to do — it resolves the majority of skipping and blank-feed cases on its own. Note the GK420d is an older model, so it does not have the newer SmartCal one-touch calibration you may have seen on ZD-series printers. Instead you use the classic FEED-button auto-calibration or Zebra Setup Utilities.
Method A: FEED-button auto-calibration (fastest)
Make sure labels are loaded correctly and the cover is fully closed, with a solid green status light
Press and hold the FEED button and keep holding it
Keep holding while the printer feeds one or more labels and the green light blinks as it measures the gap, then release
Send a test print. The label should now print in the right place without skipping.
Method B: Zebra Setup Utilities (guided)
Download and open Zebra Setup Utilities from the Zebra GK420d support page
Select your GK420d, then click Open Printer Tools → Action → Calibrate Media
The printer feeds and measures your labels. Confirm the reported label length looks right for your media.
If calibration runs but the printer still skips, the Media Type is almost certainly wrong (Fix 2), or the media sensor is dirty (Fix 5). Calibration can't succeed if the printer is looking for the wrong kind of gap.
Fix 2: Set the Correct Media Type
The GK420d has to know what kind of media it's looking at. If it's set to Continuous but you're printing die-cut labels, it will never find the gap and will feed blanks or skip. This single setting is behind a huge share of "skipping labels" reports on the GK420d.
| Your labels | Set Media Type to |
|---|---|
| Die-cut labels with a gap between them | Web Sensing / Gap (Transmissive) |
| Labels or tags with a black mark on the back | Mark Sensing (Reflective) |
| Continuous receipt / tag roll (no gap) | Continuous |
Set this on the Advanced Setup tab of the ZDesigner GK420d driver, or in Zebra Setup Utilities → Configure Printer Settings → Media Settings. After changing it, run the FEED-button calibration again (Fix 1) so the new setting takes effect.
Fix 3: Check the Printer Language (EPL vs ZPL)
Here's a GK420d-specific gotcha that trips up a lot of people. The GK420d understands two languages, EPL and ZPL, and it ships from the factory in EPL mode. If your application or driver sends ZPL to a printer in EPL mode (or the reverse), you get one of two classic symptoms: pages of garbage characters, or the printer that does nothing at all because it can't parse the command stream.
Confirm which driver you're using: the ZDesigner GK420d (ZPL) driver sends ZPL, and the ZDesigner GK420d (EPL) driver sends EPL. Pick one and be consistent
If you print garbage, you have a language mismatch — the app is sending one language while the printer expects the other
Easiest fix: install the ZPL ZDesigner driver and let it set the printer to ZPL, so the whole chain uses one language
Print a driver test page. If the test page is clean, the language is now consistent.
Newer Zebra desktop printers auto-detect the language, but the older GK420d is far pickier. If you copied a ZPL template from a ZD-series printer, or pasted raw ZPL to a GK420d still in EPL mode, garbage output is expected until you align the language.
Fix 4: Reinstall the Correct ZDesigner Driver (Windows 11)
If the GK420d prints one label and stops, prints off-center, or broke right after a Windows update, the driver is the prime suspect. Because the GK420d is an older model, Windows 11 often auto-installs a generic driver that reports the wrong label size — so the printer stops after what it thinks is the last label, or shifts everything.
Open Settings → Bluetooth & devices → Printers & scanners, select the GK420d, and Remove it
Install Zebra Setup Utilities, connect the printer via USB, and let it install the ZDesigner GK420d driver (choose the ZPL variant unless you specifically need EPL)
Open Printer Properties → Preferences and set the label size and darkness to match your media exactly
Print a Windows test page. If the test page is correct but your app still fails, the problem is in the app's page size, not the printer.
The printer prints exactly the area the driver tells it to. If the driver's page height is shorter than your physical label, the printer finishes early and stops; if it's longer, content bleeds onto the next label. Matching the driver's label dimensions to your real media — to the millimeter — fixes both.
Fix 5: Clean the Media Sensor and Printhead
If calibration and Media Type are both correct and it still skips — or if the print is faded — the media sensor or printhead may be blocked by label dust and adhesive. This is common on the GK420d because these machines are often many years old and high-mileage.
Turn off the GK420d and unplug it
Open the cover, remove the roll, and locate the media sensor in the label path
Wipe the sensor, the platen roller, and the printhead with a cotton swab or cleaning pen dampened in 99% isopropyl alcohol
Let it dry 1–2 minutes, reload the roll, and run the FEED-button calibration again
On a direct-thermal GK420d, faded output is usually low darkness or a dirty printhead — but on a well-used machine it can mean a worn printhead. If raising the darkness and cleaning the head don't help, and you often see a consistent light or missing vertical stripe, the printhead is likely worn out and needs replacing.
Bonus: Blank Labels Even Though It's Feeding
If the GK420d feeds but the label comes out totally blank, it's a direct-thermal issue, not a calibration one:
- Labels loaded upside down: the heat-sensitive side must face up, toward the printhead. Scratch a label with your fingernail — the side that turns dark is the printable side.
- Darkness too low: raise the darkness/heat setting in the driver.
- Wrong media: the GK420d "d" model is direct-thermal only — it has no ribbon and can't print on plain paper labels that require thermal transfer. (That's the GK420t.) You need genuine direct-thermal media.
The Root Cause for Many Users: The Windows Driver Itself
Notice how many of these fixes come back to the driver telling the printer the wrong thing — wrong size, wrong media type, or wrong language. That's not a coincidence. On Windows, and especially on macOS where Zebra's support for the aging GK420d is thin, the driver layer is where most GK420d headaches live. The printer's firmware is fine; the pipeline feeding it commands is what breaks.
That's exactly why some teams take the driver out of the loop. The GK420d understands ZPL, Zebra's own printer language, directly. Driverless label software like LabelInn sends ZPL straight to the printer over USB or the network — it sets the media type and label size correctly on every job, so there's no generic-driver guessing, no EPL/ZPL mismatch, no "prints one label and stops," and it works identically on macOS and Windows.
Skip the Driver Guesswork on Your GK420d
Because the Zebra GK420d speaks ZPL, LabelInn talks to it in its native language — setting media type and dimensions correctly so calibration sticks and jobs finish clean. Design labels visually or from the AI assistant, bulk-print straight from Excel, and even print from your phone. There's a free tier, and paid plans start at $14.90/month. Download LabelInn and connect your GK420d over USB or network.
Try LabelInn Free for 14 Days →Frequently Asked Questions
How do I calibrate a Zebra GK420d?
The GK420d predates SmartCal, so you use the FEED button: with the printer loaded and the status light solid green, press and hold FEED until the printer feeds one or more labels and the green light blinks, then release. For a guided run, use Zebra Setup Utilities → Open Printer Tools → Calibrate Media. Calibration teaches the printer your label length and gap so it stops skipping.
Why does my GK420d skip every other label?
It can't see the gap between labels. Either it needs calibration, or Media Type is set wrong (commonly Continuous instead of Web Sensing / Gap). Set Media Type to Gap, run the FEED-button calibration, and the skipping stops.
My GK420d prints garbage characters. What's happening?
That's an EPL vs ZPL language mismatch. The GK420d speaks both and ships in EPL mode, so if your app or driver sends ZPL to a printer expecting EPL (or the reverse) you get garbage or nothing. Install the matching ZDesigner driver (ZPL is the common choice) so the whole chain uses one language.
My GK420d prints one label then stops. What causes that?
The label size in the driver doesn't match your physical label, so the printer thinks the job is done. Reinstall the ZDesigner GK420d driver via Zebra Setup Utilities and set the label dimensions to match your media exactly. A generic Windows 11 driver is the usual trigger.
Why is my Zebra GK420d printing faded or light?
On a direct-thermal GK420d, faded print is usually low darkness or a dirty printhead. Raise the darkness in the driver and clean the printhead with 99% isopropyl alcohol. If it's still faded after that — especially with a consistent light stripe — the printhead is probably worn and needs replacing.
Can I use a Zebra GK420d on a Mac?
Zebra doesn't provide a full modern macOS driver for the older GK420d, so most Mac users can't print through the normal driver path. Because the GK420d speaks ZPL, a driverless app like LabelInn can drive it directly from macOS (and Windows), handling calibration, media type, and label size for you.