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

[TheGreek9]

When I click on "Systems Preferences" and try to scan, I get "Failed to open connection to the device (-21345). I've tried unplugging the power chord, waiting 60 seconds, nothing works. From all the related comments, it looks like a major issue coming from HP. 

[pbchair]

I have the same problem.  When is the fix coming ?

[larsvelsk]

I went to 'HP Customer Support - Software and Driver Downloads'

and downloaded the driver. It worked.

I have an officejet 6500

[Echo_Lake]

@TheGreek9 @pbchair

Thank you for posting on the HP Support Community.

Don't worry as I'll be glad to help, however, to provide an accurate resolution, I need a few more details:

• Did you make any changes on the settings of your Printer prior to the issue?
• When was the last time it worked fine?
• Is your macOS up to date?

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

[Testgonzo]

Many HP printer customers with Mac computers are encountering this problem and HP Employee Echo_Lake refuses to recognize the wide scale issue or provide a common solution.  FAIL