How to Fix Rundll Errors on Windows 10 and Windows 11

A Rundll error usually pops up at startup, naming a DLL that Windows can’t find or load. The fix depends on whether the DLL is missing, corrupted, or pointed to by a leftover registry entry. We tested the five steps below on both Windows 10 and Windows 11 machines that throw Rundll popups at boot, and the order here clears the error in almost every case without reinstalling Windows.

#What Is Rundll and Why Does It Throw Errors?

Rundll32.exe is a small Windows host process that loads a DLL into memory and runs one of its exported functions. According to Microsoft’s Windows DLL documentation, DLLs let multiple programs share code, which is why a single bad reference can trigger the popup whether the file came from Windows itself or a third-party app.

The error you see usually falls into one of three shapes, and each maps to a different cause:

1. “There was a problem starting [filename]. The specified module could not be found.” Windows tried to load a DLL that no longer exists on disk.
2. “Error loading [filename]. The specified procedure could not be found.” The DLL exists but the function Rundll32 was told to call is missing or the file is corrupted.
3. “Rundll32.exe entry point not found.” The DLL was replaced by a version that does not export the symbol Windows expects, often after a botched update or partial uninstall.

In our testing, two of the five machines showed shape 1 after we removed an old printer driver, and one Windows 11 laptop showed shape 3 after a paused Windows update left mismatched system files behind. Shape 2 is the one that warrants a malware scan first because trojans sometimes drop a fake DLL with the right name but the wrong exports.

#Method 1: Reinstall the Program Named in the Popup

When the popup names a vendor or product, the fastest fix is to remove that program cleanly and install the latest build. We tried this first on a Windows 10 desktop where the message pointed at an old Avast component, and a clean reinstall cleared the popup before the next reboot.

Steps:

1. Open Settings and go to Apps, then Apps and features on Windows 10 or Installed apps on Windows 11.
2. Find the program the popup names. The clue is usually in the file path, for example C:\Program Files\AvastSoftware\Avast.
3. Click the program, choose Uninstall, and let the vendor’s removal tool finish.
4. Restart the computer so any locked files are released.
5. Download the current installer from the vendor’s official site, run it, and reboot once more.

If the popup names only a DLL file rather than a program, search the exact filename plus “rundll” on the vendor’s support site or on the Microsoft Q&A forum before deleting anything. Many DLLs belong to drivers or runtimes that other apps still need. If the troubleshooting drags on, our guide on why Windows 10 can run slow after software changes walks through related cleanup steps.

#Method 2: Run System File Checker and DISM

System File Checker (SFC) replaces Windows-owned DLLs that have been modified or deleted, and DISM repairs the component store SFC pulls replacements from. Microsoft recommends running them in that order.

The Microsoft Support page on using SFC confirms that the tool scans every protected system file and replaces incorrect versions with correct Microsoft versions. We found that the SFC scan finished in a few minutes on the Windows 11 laptop and was nearly as quick on a Windows 10 desktop with a 512 GB SSD.

Steps:

1. Press Windows + X and choose Terminal (Admin) on Windows 11 or Command Prompt (Admin) on Windows 10.
2. Run sfc /scannow and let it finish. The scan takes about 5 to 10 minutes on most machines.
3. If SFC reports it could not fix some files, run DISM /Online /Cleanup-Image /RestoreHealth next.
4. Reboot, then run sfc /scannow once more to confirm a clean result.

When we tested this on the Windows 11 laptop with the entry-point variant, SFC alone returned “Windows Resource Protection could not perform the requested operation.” DISM finished after a while, after which a second SFC run reported it had fixed the corrupted files and the popup stopped appearing. If you boot into a repair loop instead of the desktop, work through our Windows automatic repair loop guide before trying SFC again.

#Method 3: Remove Orphaned Run Keys in the Registry

Many Rundll errors come from a Run or RunOnce key that points to a DLL the uninstaller failed to clean up. Removing the orphan stops Windows from trying to load the missing file at boot.

Manual approach:

1. Press Windows + R, type regedit, and confirm the UAC prompt.
2. Open HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run.
3. Look for entries whose Data column references a DLL path that no longer exists on disk.
4. Right-click the orphan and choose Delete. Repeat for RunOnce under both hives.
5. Reboot.

A safer alternative is to open Task Manager, switch to the Startup apps tab, and disable any item that calls rundll32.exe followed by a path you don’t recognize. We took that route on one of the Windows 10 machines because the user didn’t want to touch regedit, and the popup was gone after the next reboot.

If the registry holds keys you can’t identify, the invalid value for registry walkthrough covers safer recovery options. For deeper cleanup of leftover update files that sometimes drop these orphans, our guide on how to delete Windows update files completely is the next stop.

Safety note: never delete entries you don’t recognize. If in doubt, export the key first by right-clicking it and choosing Export so you can restore it later.

#Method 4: Run a Full Malware Scan

A subset of Rundll popups is generated by malware that loads its payload through rundll32.exe. Microsoft’s Defender threat encyclopedia documents several families that abuse Rundll32 specifically, which is why running a full scan before deleting anything system-level matters.

Steps:

1. Open Windows Security from the Start menu, then Virus and threat protection.
2. Choose Scan options, select Full scan, and click Scan now.
3. Quarantine anything Defender flags rather than deleting straight away. That preserves the log if you need to file it with IT.
4. Run a second-opinion scan with a free on-demand tool such as Malwarebytes Free if Defender comes back clean but the popup persists.
5. Reboot once both scans finish.

In our testing, only one of the five machines ended up needing this step, and Defender quarantined a suspicious DLL stored under C:\ProgramData\ that an old browser hijacker had dropped. After the reboot the Rundll popup was gone and Method 5 was no longer required.

#Method 5: Disable the Startup Item That Triggers the Popup

If you can’t identify the vendor and the SFC plus malware scans came up clean, disabling the startup entry that calls Rundll32 is the safest temporary fix.

Steps:

1. Press Ctrl + Shift + Esc to open Task Manager and click Startup apps.
2. Sort by Status, then look for entries with a generic name and an unsigned publisher.
3. Right-click each suspicious entry and choose Disable.
4. Reboot.
5. If the popup is gone, you can leave the entry disabled. If something stops working, re-enable items one at a time until you find the culprit.

This won’t repair a corrupted file, but it stops the popup so you can keep using the machine while you investigate. Pair it with Method 2 once you have time for a full SFC and DISM run.

#Should You Reinstall Windows?

A reinstall is the last resort. Before considering it, work through Methods 1 to 5 and verify your backups. The Microsoft recovery drive guide walks through building a USB recovery drive on a working machine first.

Before you reinstall:

• Back up personal files to an external drive or cloud storage.
• Note your Microsoft account and any local product keys for paid software.
• Confirm you can re-download the apps you rely on without the original installers.

If you keep hitting Stop codes alongside the Rundll popup, our DISM error 87 walkthrough often catches the underlying corruption before a full reinstall is needed.

#Frequently Asked Questions

#Bottom Line

Start with Method 1 if the popup names a program: a clean uninstall and reinstall is the lowest-risk fix and clears most third-party DLL cases without touching the registry. If the popup names only a DLL, run SFC followed by DISM in Method 2, then a full Defender scan in Method 4 before going near regedit.

The combination of an automated SFC pass, a Defender full scan, and the Task Manager startup audit in Method 5 cleared every Rundll popup we recreated on the five test machines without needing a Windows reinstall.