Scanner problem

[krap123]

When I open the scanner, the following pop up warnings appear. "HP Scanner" will damage your computer... Failed to open a connection to the device (-21345)

[Echo_Lake]

@krap123

Thank you for posting on the HP Support Community.
 

Don't worry as I'll be glad to help, I understand you are getting this error on Mac, to provide an accurate resolution, I need a few more details:

• Which application do you use to scan?
• How is the printer connected to the MAC? Do you have any anti-virus programs installed on the MAC?

Try making a standalone copy and check if that works. By this, we can conclude if this is a hardware or a driver issue.
For now, let us try these steps to resolve this issue:

• Reset the printer With the printer turned on, disconnect the power cord from the rear of the printer.
• Wait at least 60 seconds. Reconnect the power cord to the rear of the printer.
• Turn ON the printer, if it does not automatically turn on.
• Wait until the printer is idle and silent before you proceed.
  Note: HP recommends connecting the printer directly to a wall outlet rather than a surge protector or a power strip.

And, also try updating the mac OS and printer firmware. 

• Click here to download and install the latest printer firmware from your Mac.
• Click here to know different methods of updating printer firmware.

Click the Apple icon > About This Mac > Software Update and install any available update.

For more info on scanning, refer to - How to scan with an HP printer

Alternatively, use the Apple Image Capture app to scan from your Mac Refer to this document for more info.

You may also try using the HP Easy Scan app from the App Store to scan.
 

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.

[StretchMusic]

Please update to macOS 11.6. Apple resolved the Image Capture related error -21345 in the latest macOS update.

https://support.apple.com/en-us/HT212756

[krap123]

The Mac is already version 11.6. Just in case, I restarted the computer, but still the same messages.

[krap123 · Accepted solution]

Loading HP Smart App worked! Thanks much.

[StretchMusic]

HP Smart app works because the error message is related to Image Capture which is Apple's scanning app. 

If you are still having the issue after the most recent macOS update I would suggest contacting Apple to let them know it is not resolved.

[Echo_Lake]

@krap123

Thank you for posting back. 

I am glad to know that you managed to resolve the issue. Please reach out again for any further assistance.

Have a nice day ahead.