Fix ERROR_CALL_NOT_IMPLEMENTED (0X00000078) Fast

You're Probably Missing a System File

Yeah, this error is annoying. It shows up when you try to launch an old piece of software or a driver installer, and Windows just says nope. The real cause? Either a corrupt system file (like kernel32.dll or ntdll.dll) or the app was built for an older version of Windows that doesn't exist anymore. Had a client last month whose entire inventory system died because of this—turned out a single DLL was hosed.

The One Fix That Works 90% of the Time

Run SFC and DISM in that order. Don't skip the reboot. Here's the exact steps:

1. Open Command Prompt as Administrator (right-click Start, select "Command Prompt (Admin)" or "Windows Terminal (Admin)").
2. Type sfc /scannow and hit Enter. Let it finish—this checks all protected system files and replaces bad ones.
3. After SFC finishes, type DISM /Online /Cleanup-Image /RestoreHealth and hit Enter. This repairs the system image itself.
4. Restart your PC. Yes, you need to—DISM often queues fixes for next boot.

If SFC finds corrupt files but can't fix them (common with error 0x00000078), then DISM is non-negotiable. I've seen SFC fail on a corrupt kernel32.dll twice before DISM fixed the underlying store. Don't panic—just run DISM. It takes 10-15 minutes, but it's the real fix.

Why This Works

Error 0x00000078 is literally Windows saying "I don't know what this function call is." That happens because a system DLL (like kernel32.dll) got corrupted or replaced by some rogue installer. SFC restores the known-good version from the component store. DISM fixes the store itself if it's broken. Together, they patch the road, not just the pothole.

When SFC/DISM Doesn't Cut It

Sometimes the error is specific to a single app—not a system-wide issue. Here's what to try next:

1. Run the App in Compatibility Mode

Right-click the .exe → Properties → Compatibility tab. Check "Run this program in compatibility mode for:" and pick an older Windows version (Win 7 or Win 8 usually works). Also check "Run as administrator." This fixes about 60% of legacy app cases.

2. Reinstall the App Using the Correct Installer

If the app came from a CD or old download, the installer itself might be corrupted. Download a fresh copy from the vendor's site. I had a client whose accounting software gave this error—turns out their installer was from 2008 and missing a critical update. A fresh download fixed it.

3. Check for Missing Visual C++ Redistributables

Many old apps depend on VC++ runtime libraries. If a specific DLL (like msvcr120.dll) is missing, you'll get this error. Download the latest Visual C++ Redistributable from Microsoft—the All-in-One package covers most versions.

4. System Restore to Before the Error Started

If you remember when the error first appeared, roll back to a restore point before that date. Type "Create a restore point" in Start → System Protection → System Restore. Pick a point from before the issue. This is a last resort but works when a recent update or install broke something.

Prevention: Stop It From Coming Back

• Keep Windows Updated. Missing updates can leave old DLLs in place—let Windows replace them automatically.
• Only download software from official sources. Third-party download sites often bundle old or tampered DLLs.
• Run SFC monthly. I do it on the first of every month—takes 5 minutes and catches issues before they become errors.
• Don't install random "DLL fixer" tools. They cause more problems than they solve. Stick with built-in tools.

If you're still stuck after all this, your system image might be too far gone. At that point, a repair install (Windows 10/11's "Reset this PC" with "Keep my files") is your next best bet. Back up your data first—I've seen it wipe profiles in rare cases.