Canon Printer Error: “Cannot start this software because it is in use by another user”

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If your Canon printer shows the error message:
“Cannot start this software because it is in use by another user,”
it means that the Canon scanning or printing software is already running under a different user account or process on the same system, preventing a second instance from opening.

This issue is commonly seen when using Canon IJ Scan Utility, MF Scan Utility, or other Canon tools on Windows or macOS systems.

Causes of the Error
  • The Canon utility is already running in the background under another user session.
  • The software was not closed properly and is still active in memory.
  • The scanner/printer software is locked by another logged-in user (on shared or multi-user systems).
  • A system service or driver conflict is preventing the software from launching again.

Solutions

1. Close All Canon Software Completely

Windows:
  1. Press Ctrl + Shift + Esc to open Task Manager.
  2. Look for processes like:
    • Canon IJ Scan Utility
    • MF Scan Utility
    • CNMNSUT.exe, MFScanUtility.exe, or similar
  3. Select the process and click End Task.
  4. Try launching the Canon software again.

macOS:
  1. Press Command + Space and type Activity Monitor.
  2. Look for any Canon-related processes (e.g., Canon IJ Scan Utility, MF Scan Utility)
  3. Select and force quit them.
  4. Reopen the Canon software.

2. Restart the Computer
  • A full system restart ensures all background processes and software locks are cleared.
  • After restarting, open the Canon software before any other programs.

3. Log Out Other Users

If your computer has multiple user accounts, even if they’re not actively in use:

  • Log out all other users from the system.
  • Canon software cannot run simultaneously across multiple accounts.
  • Once all sessions are closed, retry launching the software.

4. Run the Software as Administrator (Windows)

Sometimes, administrative permission is required to close conflicting processes.

  1. Right-click the Canon software icon
  2. Select Run as administrator
  3. Confirm permissions and check if the software starts properly

5. Reinstall the Canon Software

Corrupted installations may cause the software to hang or not release control properly.

Steps:
  1. Go to Control Panel > Programs > Uninstall a program (Windows)
    Or drag the app to Trash (macOS)
  2. Uninstall the Canon application in question
  3. Visit Canon Support
  4. Download and reinstall the latest version for your printer model

6. Check for Driver or Firmware Updates

Outdated drivers may cause services to conflict or lock up.

  • Visit Canon’s official support site
  • Download and install:
    • Latest printer driver
    • Latest scanner driver
    • Firmware (if available for your model)

7. Disable Auto-Start for Canon Utilities (Optional)

Prevent Canon software from launching automatically at login, which may avoid this conflict in future.

Windows:
  • Open Task Manager > Startup tab
  • Disable Canon IJ Scan Utility or similar from auto-launching

macOS:
  • Go to System Settings > General > Login Items
  • Remove Canon utilities from startup

When to Contact Canon Support

Reach out to Canon support if:

  • The error persists after trying all the above steps
  • You cannot locate or close conflicting processes
  • The printer/scanner hardware is unresponsive or not detected
  • You require help in shared environments with multiple users

Canon support can guide you through advanced software handling or escalate hardware-related issues if needed.

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