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If Windows says “The program can’t start because cnb_0302.dll is missing from your computer,” “cnb_0302.dll was not found,” or “Error loading cnb_0302.dll,” the problem is usually a damaged Canon printer installation. The safest first repair is to remove the affected Canon driver and reinstall the exact driver package for your printer model from Canon’s official support site.
Do not download cnb_0302.dll from a random DLL library and copy it into System32. That may give you the wrong file, wrong architecture, or a file containing malware, while leaving the broken Canon installation untouched.
What is cnb_0302.dll?
cnb_0302.dll is associated with Canon Inkjet Printer Driver software. Public file records attribute it to CANON INC., which makes it a legitimate Canon troubleshooting subject rather than an unexplained Windows filename.
There is no reliable evidence that this file is part of Windows, Visual C++, DirectX, or .NET. No authoritative Canon file manifest publicly maps it to one specific printer model, either. In practice, the error should be treated as a Canon printer-driver installation problem until the executable raising the message proves otherwise.
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Third-party records report a 32-bit file with version 0.3.1536.1, a size of approximately 65 KB, and Canon copyright metadata. Those details are reported by file databases, not independently confirmed Canon specifications, so do not use them as a reason to download a replacement file.
The file may have been installed in a Canon program directory, a printer-driver directory, or another location used by the driver package. The exact path depends on the printer, Windows version, package, and installation method.
Causes of the error
The likely causes are:
- An incomplete or damaged Canon driver installation. A failed install, interrupted update, uninstall, or disk cleanup may remove one component while leaving Canon software behind.
- An incompatible or incorrect driver. The reported file is 32-bit, and a 32-bit Canon component may still be required on 64-bit Windows.
- Antivirus quarantine. Windows Security or another security product may have removed a driver file.
- A failed Windows upgrade or driver update.
- A missing dependency. The message may name
cnb_0302.dlleven when a file that it depends on is the real problem. - An unrelated startup item or unknown program. If the message appears without any Canon printer software installed, investigate the executable producing it before restoring anything.
The most useful clues are the exact error text, the affected Canon model, your Windows edition and build, the application name, and any DLL or executable path shown in the message.
Fix 1: Reinstall the exact Canon printer driver
This is the repair I would try first.
Identify the printer model
Check the printer’s front panel, label, original packaging, or an existing Windows printer entry. Record the complete model name, including letters and numbers. Similar Canon models can use different packages, so do not choose a driver merely because its name looks close.
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- Press Windows + I to open Settings.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Select the Canon printer.
- Note its exact model name.
If the printer is not listed, inspect the physical label or the old Canon documentation.
Check your Windows architecture
- Press Windows + I.
- Select System.
- Select About.
- Look at System type under Device specifications.
Use the Windows version and architecture offered for the exact Canon model. Do not assume that 64-bit Windows means every printer DLL must be 64-bit. A 32-bit printer application can require 32-bit driver components, and Windows handles those components through its compatibility and redirection mechanisms.
Remove the broken Canon installation
First remove the printer from Windows:
- Open Settings.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Select the Canon printer.
- Select Remove.
- Confirm the removal.
Then open Installed apps:
- In Settings, select Apps.
- Select Installed apps.
- Search for Canon.
- Remove the Canon printer software, driver utility, or setup package related to this printer.
- Restart Windows.
If several old Canon printer entries remain, remove only entries clearly connected with the affected printer or obsolete Canon installation. Avoid deleting unrelated devices without recording what they are.
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Install the replacement package
- Open Canon’s official support site in your browser.
- Search for the exact printer model.
- Choose your installed Windows version and architecture.
- Download the current printer driver or MP Drivers package.
- If Canon provides separate packages, follow the model’s installation instructions.
- Right-click the downloaded installer and select Run as administrator.
- Follow the setup wizard.
- Connect or power on the printer only when the installer requests it.
- Restart Windows if prompted.
- Print a Windows test page.
Canon uses the term MP Drivers for packages that can include the printer driver and, depending on the product, ScanGear and fax-driver components. Reinstalling the complete package is safer than replacing one DLL because it also restores dependencies, registration information, services, and configuration files.
The repair worked if the error no longer appears and the printer produces a test page. Open the application that originally failed and test printing there as well.
Outbyte Driver Updater can reduce the manual work of hunting through driver versions and checking which device packages are stale; its free scan shows detected problems, while repair and driver installation require the full version. It is optional, and Canon’s exact model-specific package remains the preferred source for this file.
Fix 2: Check whether Windows Security quarantined the file
A quarantined file can leave an otherwise installed Canon package incomplete.
- Open the Start menu.
- Type Windows Security and open it.
- Select Virus & threat protection.
- Select Protection history.
- Review recent detections.
- Open any detection associated with a Canon driver or the path shown in the error.
Do not restore a file merely because its name is cnb_0302.dll. Restore it only when the location is clearly part of the Canon installation, the file is from a trustworthy Canon package, and you understand why it was detected. If there is any doubt, remove or leave the detection in quarantine and reinstall the Canon package from the official source.
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After reinstalling, run a new scan and test the printer. If the same file is immediately quarantined again, stop repeatedly restoring it. The driver package, its signature, or another component may need investigation.
Fix 3: Install pending Windows updates
A Windows update or driver update can leave printer software in an inconsistent state.
- Press Windows + I.
- Select Windows Update.
- Select Check for updates.
- Install available updates.
- Restart Windows, even if the screen does not insist on it.
- Return to Windows Update and check again.
- Reinstall the Canon driver after Windows finishes updating.
If the problem started immediately after a Windows or Canon driver update, reinstalling the correct Canon package after the restart is more useful than copying a DLL into a system directory.
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Fix 4: Repair Windows components with DISM and SFC
cnb_0302.dll is associated with Canon software, so SFC and DISM are secondary checks rather than the primary repair. They repair Windows components and normally do not restore a third-party Canon DLL.
Use them when Windows has broader symptoms, such as damaged system features, repeated update failures, crashes, or several unrelated applications reporting missing system files.
Run DISM first
- Open Start.
- Type Command Prompt.
- Right-click Command Prompt.
- Select Run as administrator.
- Approve the User Account Control prompt.
- Enter:
DISM /Online /Cleanup-Image /RestoreHealth
- Press Enter.
- Wait for the operation to finish.
- Restart Windows if DISM reports that a restart is required.
Run System File Checker second
Open an elevated Command Prompt again if necessary and enter:
sfc /scannow
Press Enter and wait for verification to reach 100 percent.
If SFC says it found and repaired corrupt files, restart and test the original application. If it says no integrity violations were found, that does not prove that cnb_0302.dll exists or that the Canon driver is healthy. Reinstall the Canon package if the error remains.
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Fix 5: Check the application and file path
The program showing the message matters. A Canon utility, print dialog, scanning program, or startup helper is a strong indication that the Canon driver is responsible. An unknown executable requires more caution.
If Windows displays a path:
- Write down the full path to
cnb_0302.dll. - Note the name and path of the executable that requested it.
- Check whether the folder belongs to Canon or to an unrelated application.
- Right-click the executable and select Properties.
- Review the Digital Signatures tab when present.
- Scan the file with Windows Security.
If the path is inside a Canon directory, reinstall the Canon package. If it belongs to an unrelated or unknown program, do not restore a quarantined DLL or download a replacement. Uninstall the unknown program, inspect Settings → Apps → Startup, and run a full security scan.
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The error may also mean that a dependency used by cnb_0302.dll is missing. That is another reason a complete driver reinstall is preferable to replacing the named file.
Fix 6: Remove old printer entries and driver leftovers
Multiple old Canon installations can conflict.
- Open Settings.
- Select Bluetooth & devices.
- Select Printers & scanners.
- Remove duplicate or obsolete Canon printer entries.
- Open Apps → Installed apps.
- Remove old Canon utilities for the same printer.
- Restart Windows.
- Install the correct Canon package again.
If Canon supplies an uninstall utility for the model, use it rather than deleting driver folders manually. Manual deletion can leave Windows printer references behind or remove files needed by another Canon device.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Do not use System32 or regsvr32 as shortcuts
Windows does not load every DLL from System32. Applications search directories according to defined Windows DLL-loading rules, and a program may expect the file beside its executable or inside a Canon driver directory. Placing an arbitrary copy in System32 can therefore be ineffective and unsafe. Microsoft documents both the DLL search process and the security risks of unsafe DLL loading.
regsvr32 is also not a general DLL installation command. It is intended for self-registering COM or OLE DLLs that provide a DllRegisterServer entry point. There is no evidence that cnb_0302.dll should be registered manually.
Do not run:
regsvr32 cnb_0302.dll
unless Canon’s instructions for your exact driver explicitly require it. If a DLL is not self-registering, regsvr32 can produce an error without repairing the missing driver.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesWhen to use System Restore
Use System Restore only when the failure began immediately after a driver or software change and reinstalling the Canon package did not help.
- Press Windows + R.
- Type:
rstrui.exe
- Press Enter.
- Select a restore point from before the Canon installation or update failed.
- Select Next, then Finish.
- Allow Windows to restart.
System Restore changes system files, settings, and installed programs, but normally does not affect personal files. After it completes, install the correct Canon driver rather than restoring a standalone DLL.
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If the printer is old or unsupported
Canon’s current installer may not support every legacy printer. Check the printer’s archived Canon support page or use the original Canon installation media. Select the exact model and Windows version; do not substitute a similarly named driver.
If the printer works but a startup error remains, inspect Settings → Apps → Startup and remove obsolete Canon utilities that launch automatically. If only one Windows user sees the error, test another profile because a damaged per-user startup entry or installation may be involved.
For persistent failures, record:
- The complete error message
- The executable name
- The DLL path
- The Canon printer model
- Windows edition, version, and architecture
- Recent updates, antivirus detections, or uninstallations
- Any Canon installation log
That information distinguishes a broken printer package from an unrelated application that happens to request the same filename.
FAQ
Is cnb_0302.dll a Windows file?
There is no reliable evidence that it ships with Windows. Available records associate it with Canon Inkjet Printer Driver software.
Is cnb_0302.dll part of Visual C++?
No supporting evidence establishes that claim. Treat it as a Canon printer-driver component, not a Microsoft runtime file.
Which Canon printer installed it?
No authoritative public Canon source maps the filename to one specific printer model. Identify the model from Windows or the printer label, then reinstall that model’s official package.
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Is the file 32-bit?
Third-party records report a 32-bit file, but Canon has not independently confirmed those metadata details. Use the driver package offered for your exact printer and Windows installation.
Should I download the missing DLL?
No. A standalone download can be malicious, incompatible, or incomplete. Reinstall the complete Canon driver package instead.
Should I register it with regsvr32?
Usually not. regsvr32 applies to self-registering COM/OLE DLLs, and there is no evidence that this Canon driver file requires manual registration.
What if the error remains after reinstalling Canon software?
Check the executable and path that produce the message, review Windows Security Protection history, remove obsolete Canon entries, and investigate missing dependencies or unrelated startup software. Use DISM and SFC only when broader Windows corruption is also present.
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