You're trying to install or use a Kyocera printer and Windows throws ERROR_KM_DRIVER_BLOCKED (0X0000078A) at you — annoying, I know. Let's get it fixed.
Step 1: Disconnect the printer (if it's USB)
Unplug the USB cable from your computer. If the printer is on Wi-Fi or Ethernet, you can leave it connected — Windows will just block the driver install until we clear the security setting.
What you should see: Device Manager won't show the printer yet. That's normal. We're starting clean.
Step 2: Open the Local Security Policy editor
Press Win + R, type secpol.msc, and hit Enter.
If you're on Windows 11 Home or Windows 10 Home, secpol.msc doesn't exist. Skip to the "Home Edition" section below. Everyone else, keep going.
What you should see: The Local Security Policy window opens. On the left side there's a tree with "Security Settings" at the top.
Step 3: Find the driver installation policy
In the left pane, expand Local Policies, then click Security Options.
Scroll down the right pane until you see a policy called Devices: Prevent users from installing printer drivers.
What you should see: Its current state is probably "Enabled." That's the problem. When that policy is on, Windows blocks any driver it doesn't already trust — and Kyocera's KM driver falls into that bucket on a lot of corporate-managed machines.
Step 4: Disable the policy
- Double-click Devices: Prevent users from installing printer drivers.
- Select Disabled.
- Click Apply, then OK.
What you should see: The policy now reads "Disabled" in the Security Setting column. No reboot is needed, but if the printer install still fails, reboot anyway — Group Policy sometimes caches.
Step 5: Reinstall the Kyocera driver
Now go grab the correct driver. Don't use whatever Windows Update offers you. Go to Kyocera's site and download the KX Driver for your exact model. For most ECOSYS and TASKalfa printers, that's the KX v6 or newer.
Run the installer. When it asks, plug the USB cable back in.
What you should see: The install completes without the 0X0000078A error. The printer shows up in Settings > Bluetooth & devices > Printers & scanners.
Windows Home Edition? Use the Registry instead
Home editions don't ship with secpol.msc, so you'll edit the registry directly. Back it up first.
- Press
Win + R, typeregedit, hit Enter. - Go to:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers - If the Printers key doesn't exist, right-click Windows NT, choose New > Key, and name it
Printers. - Select Printers. On the right, look for RestrictDriverInstallationToAdministrators. If it's not there, right-click empty space and choose New > DWORD (32-bit) Value, name it exactly that.
- Double-click it and set the value to
0. - Click OK, then close Registry Editor and reboot.
What you should see: After the reboot, the printer install runs without the KM_DRIVER_BLOCKED error.
Real-world trigger: This error usually pops up on company laptops where IT has pushed a hardened Group Policy, or right after a Windows cumulative update that flips the printer driver install policy back to restricted. If you installed KB5034441, KB5031354, or any 2024 patch on a managed machine, that's your likely culprit.
Why this actually works
Windows has a security feature that only lets administrators install printer drivers by default — it's designed to stop malware from sneaking in fake print drivers. The Kyocera KX driver isn't signed in a way Windows trusts out of the box, so when the policy is enforced, Windows blocks it and reports 0X0000078A. Turning that policy off tells Windows "this user is allowed to install print drivers," and the block goes away. It's not the driver that's broken. It's Windows saying no.
Less common variations
- Error persists after disabling the policy: Check if you also have Point and Print Restrictions enabled under Computer Configuration > Administrative Templates > Printers. Point and Print can override the local policy on domain-joined machines.
- Universal Print or IPP Everywhere: If you're installing via IPP, the driver block can still apply. Use the manufacturer's full package instead of the Microsoft IPP class driver that Windows auto-selects.
- Printer shows up but prints garbage: That's a wrong-driver symptom, not a block. Uninstall the printer in Settings, delete the leftover driver under Print Server Properties > Drivers, and reinstall.
- Domain-joined machine: Local policy changes may get overwritten at next Group Policy refresh. Ask whoever manages your domain to set the policy at the domain level, or you'll be doing this dance every reboot.
- 0x0000078A on Windows Server: Same fix, but check the Print Spooler service. If it's stopped, start it before reinstalling the driver.
Preventing it from coming back
The policy is the whole battle here. Once you've turned it off, it stays off unless something changes it. A few things to watch:
- Windows updates: Big cumulative updates can reset policy defaults. If the error returns, check the same policy first. Takes 30 seconds.
- Domain pushes: If you're on a company machine, the domain controller wins every time. Ask IT to whitelist your Kyocera driver or set an exception.
- Skip third-party driver updaters. Those "driver booster" tools often drop unsigned drivers and make this worse. Get drivers from Kyocera directly.
- Keep the KX Driver current. Kyocera updated their signing certificates around 2022 — old versions of the driver hit signature blocks on newer Windows builds. Grab the latest.
Do those four things and you probably won't see 0X0000078A again.