cnbjop9s.dll may produce this message: “The program can’t start because cnbjop9s.dll is missing from your computer.” It is generally associated with a Canon Inkjet Printer Driver package, so the safest fix is to repair or reinstall the complete Canon printer driver rather than download the DLL separately.
Which fix applies to you
Use the path that matches when the error appears:
- While printing, opening Printer Properties, or adding a Canon printer: remove and reinstall the exact Canon printer driver.
- Immediately after a Canon or Windows update: restart, install pending Windows updates, then reinstall the Canon driver.
- After antivirus reported a threat: check Windows Security Protection history before restoring anything.
- After disk cleanup or manual file removal: reinstall the printer package. Do not copy a replacement into
System32. - With several old Canon printers installed: remove unused queues and stale driver packages.
- After reinstalling the driver, when the same error remains: check the exact file path, missing dependencies, Print Spooler errors, and Event Viewer.
- When the file is in a user-writable folder: treat it as suspicious and scan the computer.
The error may say “cnbjop9s.dll was not found,” “Cannot find cnbjop9s.dll,” “Error loading cnbjop9s.dll,” or “The specified module could not be found.” The last message can indicate a missing dependency rather than the named DLL itself.
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What cnbjop9s.dll is
Public file records associate cnbjop9s.dll with Canon’s Windows inkjet-printer driver software. It is a driver payload, not a Microsoft Visual C++ runtime file, DirectX component, .NET file, or ordinary Windows application DLL.
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Canon printer drivers convert print data from Windows applications into a format the printer understands. The required package depends on the printer model and Windows version.
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Older records place the file inside a Windows Driver Store path similar to:
C:WindowsSystem32DriverStoreFileRepositoryprncacla.inf_...I386
That location does not mean the file is a normal Windows core component. The Driver Store contains trusted Windows and third-party driver packages, and its files should not be manually added, removed, or edited. See Microsoft’s Driver Store guidance.
The available public records contain conflicting architecture information. Some describe older 32-bit driver payloads while another record labels a copy as x64. Do not choose a replacement based on a filename, reported size, or an isolated architecture label.
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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 glitchesFirst, verify the file and the trigger
Before changing anything, record what Windows is actually reporting.
1. Capture the exact error path
If the dialog shows a path, write it down. A file under a Canon installation directory or the Windows Driver Store is more consistent with a printer package than a copy under:
Downloads%Temp%- An unfamiliar application folder
- A user-writable folder with a random name
A suspicious location does not prove malware, but it requires a scan before the file is trusted.
2. Check the file properties
If a copy of the file exists:
- Right-click it and select Properties.
- Open the Details tab.
- Check the description and company fields.
- Open Digital Signatures, if present.
- Select the signature and choose Details.
- Confirm whether Windows reports that the signature is valid.
The absence of a signature alone does not prove that the file is malicious, particularly for an old driver payload. However, an unexpected path, invalid signature, or recent unexplained appearance is a reason not to restore or execute it manually.
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If the problem began suddenly:
- Open Windows Security.
- Select Virus & threat protection.
- Choose Protection history.
- Review detections and quarantined items.
- Expand any item related to the Canon driver.
Do not disable antivirus protection globally. If the file was quarantined, reinstall the driver from Canon first. Restore or allow the item only when its original path, signature, and installation source are verified. Microsoft explains these decisions in its Protection History instructions.
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Fix 1: Reinstall the complete Canon printer driver
This is the primary repair when printing or printer setup triggers the error.
Remove the printer
In Windows 11:
- Open Settings.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Choose the affected Canon printer.
- Select Remove.
- Confirm the removal.
In Windows 10:
- Open Settings.
- Select Devices.
- Select Printers & scanners.
- Select the Canon printer.
- Choose Remove device.
- Confirm.
Disconnect the printer’s USB cable while removing it if Windows keeps rediscovering the device.
Remove an unused Canon driver package
If several Canon models or older packages were installed:
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- Press Windows key + R.
- Enter:
printui.exe /s /t2
- Press Enter.
- Open the Drivers tab.
- Select a Canon driver that is no longer used.
- Choose Remove.
- Select Remove driver and driver package, when offered.
- Restart Windows.
Do not remove a package still used by another working printer. If unsure, remove only the printer queue and reinstall the current package first.
Install the correct package
- Identify the exact printer model from its label or the printer’s existing Windows entry.
- Open Canon’s official support and download area.
- Search for that model.
- Select the installed Windows version.
- Download the complete printer driver or Canon printer software package.
- Right-click the installer and select Run as administrator.
- Follow the setup prompts.
- Connect or power on the printer only when the installer requests it.
- Restart Windows after installation.
- Print a test page from Settings → Printers & scanners → Canon printer → Printer properties.
The repair worked if the printer installs without the DLL message, Printer Properties opens normally, and a test page completes. If Canon does not offer a current Windows 10 or Windows 11 package for the model, use the newest supported driver listed by Canon or a compatible Windows driver path. Do not substitute an isolated DLL.
Manually comparing 32-bit and 64-bit files is unreliable because a 32-bit component can be valid inside a printer-driver subsystem on 64-bit Windows. Check Settings → System → About → System type, then use the package Canon provides for that printer and Windows installation.
When manually hunting through driver pages means guessing among old packages and stale devices, Outbyte Driver Updater can scan for outdated or damaged drivers; its free scan identifies problems, while repair and driver installation require the full version. It is optional, and the exact Canon model-specific package remains the preferred source.
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Fix 2: Install Windows updates and restart
A Windows update can change printer subsystems or expose an old driver problem.
- Open Settings.
- Select Windows Update.
- Choose Check for updates.
- Install all available updates.
- Restart when prompted.
- Run the Canon driver installer again after Windows finishes updating.
If the error started immediately after a driver change and reinstalling does not help, use Settings → System → Recovery → System Restore when that option is available. Select a restore point from before the failure and review the affected programs before confirming. System Restore changes system files, registry settings, and installed programs but does not normally change personal files. Microsoft documents this process in its System Restore guidance.
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Fix 3: Repair Windows components with DISM and SFC
Use these commands when Windows component corruption, update damage, or driver infrastructure problems are possible. They do not guarantee restoration of a third-party Canon payload.
- Open Start.
- Type
Command Prompt. - Right-click Command Prompt.
- Select Run as administrator.
- Approve the User Account Control prompt.
- Run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for it to complete.
- Then run:
sfc /scannow
- Restart Windows.
- Test the printer again.
Microsoft recommends running DISM before SFC. Its SFC and DISM instructions explain the results.
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Repeating repair commands without knowing whether the Windows image or the printer package is at fault can waste time. Outbyte PC Repair can scan for Windows problems and show what it identifies; the free scan reports issues, while repair requires the full version. It is not required, and reinstalling the Canon driver is still the definitive fix for a missing Canon payload.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Fix 4: Check the Print Spooler and dependencies
If the printer installs but printing still fails:
- Press Windows key + R.
- Enter
services.msc. - Press Enter.
- Find Print Spooler.
- Confirm its status is Running.
- If it is stopped, right-click it and select Start.
- If it is already running, select Restart.
- Try a test page again.
“The specified module could not be found” can mean a dependency required by the driver is absent. Check Event Viewer by right-clicking Start, selecting Event Viewer, and reviewing Windows Logs → System around the time of the failure. Record any printer, spooler, application, or side-by-side errors.
If the printer works but a popup continues, remove obsolete Canon utilities, old queues, and unused Canon driver packages. Reinstall only the software required for the current model.
Do not copy the DLL or use regsvr32
Do not download cnbjop9s.dll from a random DLL archive or copy it into:
C:WindowsSystem32C:WindowsSysWOW64- An application directory
- The Driver Store
A downloaded copy may contain malware, have the wrong architecture, belong to a different driver release, or leave the damaged package and missing dependencies untouched.
regsvr32 is intended for DLLs that provide registration entry points such as DllRegisterServer. There is no reliable evidence that this printer-driver payload requires COM registration. Running the following commands is therefore not a routine repair:
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regsvr32 cnbjop9s.dll
regsvr32 /u cnbjop9s.dll
They can produce an entry-point error and do not rebuild a printer driver. Microsoft’s regsvr32 documentation explains when the command applies.
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Is cnbjop9s.dll a Windows system file?
It is associated with Canon inkjet printer-driver software, not a general Windows runtime. It may appear inside Windows-managed driver storage because Windows stores third-party driver packages there.
Is it malware?
The filename alone does not establish that it is malicious. Verify the path, scan the file, and inspect its digital signature. A copy in a temporary or user-writable folder deserves extra scrutiny.
Which Canon printer owns this file?
No single Canon model can be identified from the filename alone. The correct driver depends on the installed printer model and Windows version.
Does reinstalling the DLL fix the problem?
Usually not. The missing file may be one part of an incomplete package, or the real problem may be a missing dependency, spooler failure, or incompatible legacy driver.
What should I give a technician?
Provide the printer model, Windows edition and build, exact error text, full file path, the point at which the error appears, recent update or antivirus history, and the file’s signature result.
What if Canon no longer supports the printer?
Try the newest supported Canon package or a compatible Windows printer-driver path. If no compatible driver exists, replacing only the DLL is unsafe and unlikely to provide a reliable solution.
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