"Failed to open a connection to the device (-21345)"

[perry227ma]

I'm trying to scan over a wifi network, which used to work fine and now never does. 

I get the error: "Failed to open a connection to the device (-21345)"

I have tried both the HP suggested solution (resetting the printer) and the Apple suggested solution (resetting the printing system) and I still get this error every time. Can anyone help?

[RocketNige]

I had the same problem (Mac OS X 11.6 Big Sur, HP M283FDW Laser printer). Following all the advice as you've done yourself, but no success.

In the end I took a "belt and braces" approach which worked for me, and that was to delete the printers, then reset the system, but not before changing the IP6 settings of the printer. As follows.

(1) With the printer already installed in OS X, and the scanner error being generated, I installed the HP Smart app and confirmed that I could scan over wifi using that app, even though the native Mac dialogue was generating the error message. (This worked OK - HP Smart Scan could see and use the scanner. It's a massive pain in the neck to have to register with HP to scan via wifi in that application - but that's what you have to do. Move on...)

(2) Turn off the printer IP6 functionality via the advanced options in HP Smart (it's an interface to the printer, so that changes a printer-side setting) - so only IP4 is used. Don't forget to click the APPLY dialogue after you untick IP6. First time I tried it, I missed that, and found IP6 still turned on when I logged in again. Double check that you are only using IP4 by exiting HP Smart, then opening it and checking the settings, before moving to the next step.

(3) Now DELETE all the printers in your OS X Printers & Scanners preference item, using the - sign to remove each one. (This isn't listed in the advice you pointed to. Is it necessary? All I know is that this sequence worked for me.)

(4) Once you've removed the printers, right click in that (now empty) printer list pane, and Reset the Printer System.

(5) Restart the Mac

(6) Now install the printer again via the Native OSX Printers & Scanners dialogue.

For me, this solved it - I can scan over wifi using the OS X native app, without HP Smart software running. I've not yet uninstalled HP Smart, but I certainly don't need to have it running to scan over wifi with the native dialogue. I've restarted my machine a couple of times for other reasons, and I'm still able to do that, so it looks like a robust fix.

YYMV but it's worth a try.

Nigel