A recent Windows update or a corrupted spooler file is the most likely cause. Run the Windows Print Troubleshooter (Settings > System > Troubleshoot > Other troubleshooters > Printer).
If you continue to see “F166” or “400” after installing the correct driver, focus on resolving network errors (for code 400) or hardware issues (for code F166). When in doubt, Canon’s customer support (1-800-OK-CANON in North America) can provide model-specific guidance based on your printer’s serial number. Canon Printer F166 400 Driver
Temporarily disable your antivirus firewall. Connect the printer via USB directly to the laptop/PC for the initial setup. Once the driver is installed, you can switch to Wi-Fi. A recent Windows update or a corrupted spooler