"Failed to open a connection to the device (-21345)" Scanning over wifi network

[JoeSkelley]

Apple has stated that macOS 11.6 fixes the error "Failed to open a connection to the device (-21345)" in the article 'You do not have permission to open the application' when using a scanner on Mac

using the latest MacOS 10.15.4, over a wifi network, the error occurs using scan link in printer control and HP Easy Scan and Image Capture. Printing works but can not connect to the scanner.

[Jay_G24]

Hi @JoeSkelley

Welcome to the HP Support Community. I'd be happy to assist you with the  "Scan error" issue. 

 Let's try a power reset on the printer-

Reset the product

1. With the printer turned on, disconnect the power cord from the rear of the printer.

1. Unplug the power cord from the wall outlet.
2. Wait at least 60 seconds.
3. Plug the power cord back into the wall outlet.
4. Reconnect the power cord to the printer.
5. Turn the printer on. HP recommends plugging the printer directly into a wall outlet.

Try and scan, if the issue persists try the below steps.

try updating the printer's firmware - HP Printers - Updating or Upgrading Printer Firmware 

Update mac-How to update the software on your Mac

Hope this helps! Keep me posted. 

Please click “Accept as Solution” if you feel my post solved your issue, it will help others find the solution.

Click the “Kudos, Thumbs Up" on the bottom right to say “Thanks” for helping!

Have a great day! 

[zembrowski · Accepted solution]

Had the same issue. This worked for me (from Apple Support Community - https://discussions.apple.com/thread/2535764😞

Try a reset of the printing system.

How to Reset the Printing System

1. Open System Preferences > Print & Fax
2. Move your mouse over the Printers list
3. Hold down the Control button and click the mouse (or right click if supported).
4. Click "Reset printing system ..."
5. Restart your Mac

This will remove your printer and scanner queues but not your drivers. So you will only need to add your printer and scanner queues again.

[ReyRey3]

Hi, thanks for this, though I tried and it did not work.  I ended up having to rest the printing system altogether and reboot my Mac.  Appreciate the help, though!

[ReyRey3]

This worked like a charm.  Thank you!

[zembrowski]

Glad I could help.

I think you marked the wrong post as a solution.

[JoeSkelley]

Likely. I couldn't see the correct answer to mark it.   

[Geericho]

The solution that worked for me was to disable IPv6 on the printer's web interface. On my Office Jet Pro 7740 that meant opening the web interface, selecting Network, General, Network protocols. Then deselect - Enable IPv4 and IPv6. Then select Enable IPv4 only.