Windows Errors? Fix Them Before They Spread
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchcnmur.dll errors usually appear as “cnmur.dll is missing,” “cnmur.dll was not found,” or “Error loading cnmur.dll.” The file belongs to Canon printer software, not to Windows, DirectX, Visual C++, or .NET.
The 60-second answer
cnmur.dll is identified as MP Printer Driver Localizable Resource, a component of Canon’s BJ Raster Printer Driver for Windows NT4.0. It is associated with older Canon BJ and Bubble Jet printers and their driver packages.
The safest repair is to remove the damaged Canon printer software and reinstall the complete driver package for the exact printer model. Do not download cnmur.dll by itself and copy it into System32 or SysWOW64.
If the error appeared after removing an old printer, restoring a system image, running antivirus cleanup, or using disk-cleanup software, Windows may still have a Canon startup entry, print monitor, or driver reference that expects the file.
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What is cnmur.dll?
The reported internal description of cnmur.dll is MP Printer Driver Localizable Resource. Available file metadata identifies Canon Inc. as the publisher and associates the file with the Canon BJ Raster Printer Driver for Windows NT 4.0.
That makes it a printer-driver resource DLL. It is not a core Windows component and is not normally repaired by installing:
- Microsoft Visual C++ Redistributable
- DirectX
- .NET
- A Windows language pack
- A game runtime
- A general system DLL package
The file belongs to an obsolete Canon driver family used by legacy printers and older Windows releases. Canon documentation for older BJ printers separates the BJ Raster Printer Driver from Windows itself and identifies different driver families for systems such as Windows 95/98, Windows NT 4.0, and Windows 2000.
Public file indexes also report cnmur.dll as a 32-bit Win32 DLL. That information should be treated as file metadata rather than a guarantee about every copy encountered online. A similarly named file, cnmur61.dll, belongs to a different reported Canon printer-driver generation and should not be substituted.
Why does the error appear?
The message tells you that a program attempted to load a Canon component and Windows could not complete that request. Common triggers include:
- An incomplete Canon printer-driver installation
- A damaged or partially removed printer package
- An old printer being uninstalled while a startup component remains
- Antivirus quarantine or deletion
- A restored system image containing outdated printer references
- Disk cleanup removing a file without removing its parent software
- A driver package intended for another Canon model or Windows generation
- A missing dependency beside the DLL
- A stale print monitor or printer-port entry
The exact trigger depends on when the message appears.
If it appears while printing or opening printer properties, the Canon driver is the primary suspect. If it appears at every startup even though no printer is connected, an old Canon utility or print-monitor entry may still be launching. If a completely unrelated game reports the file, treat that as suspicious or as a damaged application installation. cnmur.dll is associated with Canon printer software, not known game middleware.
Fix 1: Identify and reinstall the complete Canon printer package
This is the most likely fix. Replacing the whole driver package repairs the files, registry entries, print monitor, language resources, and printer configuration together.
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Find the printer model
Check the label on the printer, its original documentation, or the printer entry in Windows.
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- Press Windows + I.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Open any Canon printer listed there.
- Record the exact model name.
If the printer is not listed:
- Right-click Start.
- Select Device Manager.
- Expand Printers, Print queues, and Universal Serial Bus controllers.
- Look for a Canon entry, an unknown device, or a device with a warning icon.
Do not guess the model from the name of the DLL. Several Canon printer generations used related driver components, and a package for another model may not contain the files your system expects.
Remove the old Canon software
First remove the application package:
- Press Windows + I.
- Select Apps.
- Select Installed apps.
- Search for Canon.
- Remove the printer driver, Canon printer utility, or setup program associated with the affected printer.
- Restart Windows.
On older Windows 10 installations, use:
- Open Control Panel.
- Select Programs.
- Select Programs and Features.
- Uninstall the Canon printer software.
Then remove the printer object:
- Open Settings.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Select the old Canon printer.
- Choose Remove.
If Windows says the printer is in use, restart the computer and try again. Disconnecting the printer before removing the package can also prevent the old device from being automatically reused during setup.
Remove an orphaned driver if necessary
Only do this when the Canon package has already been uninstalled.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitches- Press Windows + R.
- Enter:
printui.exe /s /t2
- Press Enter.
- Select the Drivers tab.
- Select the old Canon driver.
- Choose Remove.
- Select Remove driver and driver package if Windows offers that choice.
- Restart Windows.
Do not remove a driver that is still used by another working printer. If you are unsure, leave this step alone and continue with the official installer.
Download and install the correct package
Use Canon’s official support site, search for the exact printer model, select the version of Windows you are running, and download the complete printer software package if one is available. Microsoft also recommends obtaining printer drivers through Windows Update or the printer manufacturer.
Run the installer normally. If the installer asks you to connect the printer, connect it only when instructed. Restart Windows when setup finishes, then print a test page.
You know this repair worked when:
- The error no longer appears
- The Canon printer remains listed after restarting
- Printer Properties opens normally
- A test page prints
- The Canon utility opens without requesting
cnmur.dll
If the package refuses to install, check the model and operating-system selection again. An NT 4.0-era package may not work on current Windows 10 or Windows 11, even when compatibility mode allows the installer to start.
Outbyte Driver Updater can reduce the manual work of hunting through old driver packages and guessing which installed drivers are stale; its free scan shows what it identifies, while driver installation is handled by the full version. For this specific file, use the exact Canon package first because a generic driver updater cannot guarantee support for an obsolete printer model.
Fix 2: Check Windows Security quarantine
A security scan may have quarantined or removed a Canon DLL. Do not restore a loose copy from the internet just because it has the same filename.
- Open Start.
- Search for Windows Security.
- Open it.
- Select Virus & threat protection.
- Select Protection history.
- Review recent detections.
- Open any detection that names the Canon printer software or
cnmur.dll.
If the file came from a verified Canon installer and the detection is clearly a false positive, follow Microsoft Defender’s restore instructions. If you cannot verify the source, leave the file quarantined and reinstall the driver from Canon instead.
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Restoring a questionable DLL can reintroduce malware or cause Defender to detect it again. A clean driver installation is safer than restoring a file without its original package, dependencies, and digital-signature context.
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- Open Windows Security.
- Select Virus & threat protection.
- Select Quick scan.
- Review the result in Protection history.
Fix 3: Check the driver architecture and generation
Older Canon printer packages may contain 32-bit components. A 32-bit resource DLL is not interchangeable with a 64-bit DLL, and Windows does not make unrelated architectures compatible by renaming files.
Do not:
- Replace
cnmur.dllwithcnmur61.dll - Copy a file from another Canon printer package
- Use a file advertised for a different Windows generation
- Copy a random DLL into
System32 - Copy a random DLL into
SysWOW64
On 64-bit Windows, System32 is used for many 64-bit system components, while SysWOW64 supports 32-bit Windows-on-Windows components. That naming is easy to misunderstand, but neither folder is a general-purpose location for third-party printer resources.
If the Canon installer is 32-bit, that alone does not mean it is compatible with modern Windows. The entire driver, print processor, port monitor, and installer must support the operating system.
If Canon no longer offers a compatible package for the model, use one of these paths:
- Check whether Windows automatically offers a compatible built-in printer driver.
- Add the printer through Settings > Bluetooth & devices > Printers & scanners > Add device.
- Try the printer’s supported generic driver if Windows presents one.
- Use the printer from a compatible older Windows installation.
- Replace the printer with a model supported by the current operating system.
Do not force-install an unrelated Canon package merely because its name contains the same CNM prefix.
Fix 4: Repair the Windows component store
SFC and DISM repair Windows components. They normally cannot recreate a missing third-party Canon DLL, but they are appropriate when the computer also has damaged Windows features, update failures, crashes, or other system-file errors.
First run DISM:
- Right-click Start.
- Select Terminal (Admin) or Windows PowerShell (Admin).
- Approve the User Account Control prompt.
- Enter:
DISM /Online /Cleanup-Image /RestoreHealth
- Wait for it to finish.
- Restart Windows.
Then open an elevated Terminal again and run:
sfc /scannow
Wait until verification reaches 100 percent. Restart the computer and test the printer.
Possible results include:
- Windows Resource Protection did not find any integrity violations: Windows system files appear intact.
- Windows Resource Protection found corrupt files and successfully repaired them: Restart and test again.
- Windows Resource Protection found corrupt files but was unable to fix some: Run DISM again, restart, and repeat SFC. If the problem remains, focus on the Canon package rather than expecting SFC to supply it.
If you want an automated way to avoid repeatedly guessing which Windows components need attention, Outbyte PC Repair can scan for reported system problems; the free scan identifies issues, while repair is performed by the full version. It is optional and does not replace reinstalling the Canon driver that owns cnmur.dll.
Fix 5: Use System Restore after a recent driver change
System Restore is useful when cnmur.dll worked before a printer installation, removal, update, or cleanup operation.
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- Press Windows + R.
- Enter:
rstrui.exe
- Press Enter.
- Select Next.
- Choose a restore point from before the error began.
- Select Scan for affected programs if available.
- Confirm the restore point.
- Select Finish.
System Restore rolls back system files, registry settings, drivers, and installed programs. It does not normally remove personal documents or photographs.
After Windows returns to the desktop, test the printer. If the error returns, the underlying Canon installation is still damaged, so reinstall the correct package rather than repeatedly restoring the system.
If no restore point exists, Windows 11 may offer Settings > System > Recovery > Fix problems using Windows Update > Reinstall now. This repairs the current Windows installation while preserving apps, files, and settings where supported, but it is not a substitute for installing the Canon printer software.
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Fix 6: Remove a stale Canon startup or print reference
If the error appears on every startup but no Canon printer is currently used, the file may be requested by leftover software.
Start with the safe removal path:
- Open Settings > Apps > Installed apps.
- Search for Canon.
- Remove unused Canon printer utilities.
- Restart Windows.
- Open Settings > Bluetooth & devices > Printers & scanners.
- Remove obsolete Canon printers.
Then inspect the print environment:
- Press Windows + R.
- Enter:
services.msc
- Press Enter.
- Find Print Spooler.
- Right-click it and select Restart.
Do not disable the Print Spooler permanently. It is required for normal Windows printing.
You can also check startup entries:
- Press Ctrl + Shift + Esc.
- Select Startup apps.
- Look for an old Canon utility.
- Disable only entries you recognize as belonging to the unused printer.
- Restart.
If the startup message continues, use Settings > Apps to remove the remaining Canon software rather than deleting DLLs manually. A stale reference may be stored in a printer monitor, scheduled task, or driver package, and deleting the file does not remove that reference.
Why regsvr32 usually does not fix cnmur.dll
regsvr32 is intended for DLLs that expose a registration entry point such as DllRegisterServer. A localized printer-resource DLL is not ordinarily a self-registering COM or ActiveX component.
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Running this command is therefore not a standard repair:
regsvr32 cnmur.dll
It may produce an error saying that the module was loaded but the entry point was not found, or that registration failed. That does not prove the file is bad. It usually means the command is inappropriate for that type of DLL.
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Use the Canon installer instead. It places the resource file where the driver expects it and creates the required printer configuration.
What if the error appears in a game or unrelated program?
cnmur.dll is associated with Canon printer software. A game or unrelated application should not normally need it.
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- Verify the game files through its launcher.
- Reinstall the game if verification fails.
- Scan the computer with Windows Security.
- Check which startup process or shortcut actually displays the error.
- Remove obsolete Canon software if the message occurs independently of the game.
Do not download the DLL to satisfy an unrelated application. A wrong DLL can hide the original problem while introducing an architecture mismatch or security risk.
Frequently asked questions
Is cnmur.dll a Windows file?
No. Available evidence identifies it as a Canon printer-driver resource associated with the BJ Raster Printer Driver for Windows NT 4.0.
Is cnmur.dll 32-bit or 64-bit?
Public metadata reports a 32-bit Win32 DLL. Treat that as a description of the reported legacy file, not as permission to download an arbitrary copy. The correct architecture comes from the complete driver package for the printer.
Should I download cnmur.dll from a DLL website?
No. Standalone downloads can contain malware, the wrong architecture, the wrong driver generation, or a modified file. They also do not repair the printer package that requested the DLL.
Should I copy it into System32 or SysWOW64?
Normally no. Those folders are not general storage locations for third-party printer resources. Install the complete Canon driver instead.
Should I install Visual C++ or DirectX?
Generally no. cnmur.dll is identified as a Canon printer-driver resource, not a Visual C++, DirectX, or .NET runtime file.
Can SFC restore cnmur.dll?
Normally no. SFC repairs protected Windows system files. It does not usually restore a missing Canon driver component.
Can I replace it with cnmur61.dll?
No. Similar filenames can represent different Canon driver generations or localized-resource packages. Use the file supplied by the exact printer installer.
What if my printer is too old for Windows 11?
Check Canon’s support page for the exact model and operating system. If no compatible package exists, try a Windows-provided compatible driver or use a supported replacement. Compatibility mode may help an installer start, but it cannot guarantee that the old driver will function correctly.
Why does the error appear when I do not own a Canon printer?
A stale Canon printer utility, startup entry, print monitor, or restored driver reference may remain. Remove unused Canon software and obsolete printers, restart the Print Spooler, and reboot. If the message continues, identify the startup process that launches it rather than deleting the DLL.
Quick Recap
Final checklist
Use this order:
- Identify the exact Canon printer model.
- Remove the damaged Canon software and obsolete printer entry.
- Install the complete official Canon package if it supports your Windows version.
- Check Windows Security Protection history.
- Confirm you are not mixing
cnmur.dllwithcnmur61.dll. - Restart the Print Spooler and remove stale Canon startup entries.
- Run DISM followed by
sfc /scannowif Windows itself is damaged. - Use System Restore if a recent driver change caused the error.
- Avoid standalone DLL downloads, manual System32 copying, and routine
regsvr32commands.
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