Failed to Open a Connection to the Device (-21345)

[diane9945]

I am using an OfficeJet 5740 All In One with a Mac using Sequoia. My printer is working fine but I cannot connect to the scanner. I get a message like the ones listed above. I have tried every solution offered, however, none of them have worked. I need help or do I need a new printer/scanner? I have been using this same exact system for several years with no problems. Just started last week.

[Sneha_01]

Hi @diane9945 

Welcome to HP Support Community.

Thank you for posting your query, I will be glad to help you.

It sounds like you're dealing with an issue where your OfficeJet 5740 printer works fine, but you're unable to connect to the scanner on macOS Sequoia, and you’re seeing the error: “Failed to Open a Connection to the Device (-21345).”

Given that you've been using this setup for years without issues, it seems like this might be related to a recent software or macOS update. There are several troubleshooting steps we can go through to try to resolve this issue without needing to replace the printer/scanner.

1. Restart the Printer and Mac

• Power cycle both the printer and your Mac. Turn off your printer, wait for about 30 seconds, and then turn it back on. Do the same for your Mac.
• Disconnect and reconnect the printer from your network (if using Wi-Fi) or unplug/replug the USB cable.

2. Update Printer Drivers and Software

• Since you're using macOS Sequoia, ensure that you have the latest HP drivers installed. HP may have released an updated driver or patch for compatibility with macOS 15 Sequoia.
  • Visit the HP Support page and download the latest HP Easy Start or HP Smart software for macOS. This will ensure that you have the latest drivers and scanning software.
• Update macOS: Ensure that your system is fully updated with the latest macOS updates and patches (even minor ones), as they can often fix bugs related to connectivity and peripherals.

3. Reinstall HP Scan Software

Since you’re seeing an error related to the scanner, the software that controls the scanner may be misconfigured or corrupted. Try reinstalling the scanning software:

1. Delete the current HP software from your Mac. Go to Applications, find HP Easy Start or any HP scanning software you’ve installed, and drag it to the trash.
2. Reinstall the software from the HP website or the Mac App Store (download HP Smart or HP Easy Start for the latest version).
3. Restart your Mac and check if the scanner works.

You can also can switch to AirPrint: On macOS and OS X, most HP printers work with Apple AirPrint to provide full-quality printing without the need to download or install drivers.

I hope this helps.

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