HP smart Scanning is currently unavailable for HP Laserjet Pro MFP M28a

[Snoopyfans]

The HP smart app keeps saying that "Scanning is currently unavailable. Please select Home to check that your printer is connected and active. Once connected, return here to scan."
The fact is my printer is connected, able to print and WAS able to scan. After searching through the forum, I found several posts regarding the similar cases. I followed their solution, run print and scan doctor, reboot, repair and reset apps, uninstall and reinstall. However the message is still prompting.

I could now use the app HP scan for scanning job but it would be better to have all functions run in the HP Smart. Or may the scanning no more functioning in HP Smart?

[Echo_Lake]

@Snoopyfans

Thank you for posting on HP Support Community.
 

Don't worry as I'll be glad to help, I have a few troubleshooting steps we could try to fix the issue:  
 

Firstly, let's update the printer's firmware, refer - HP Printers - Updating or Upgrading Printer Firmware

If the issue persists, follow the next steps. Uninstall the app from your Windows 10 device through the All Apps list.

1. In Windows, search for and open Apps & features.
2. Click HP Smart in the list of apps, and then click Uninstall.

And, install HP smart app from here: https://support.hp.com/in-en/document/c04675142

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.

[Snoopyfans]

Thanks for your help but the issue persists.

I've download the updated firmware following the instruction below

and get this dialogue box, click on the send firmware then finally get a smiley on the dialogue box.

After these, I tried on HP Smart, issue persisits, uninstall and reinstall, issue persists.

[Echo_Lake]

@Snoopyfans

Thank you for posting back.

Let's try HP Easy start: https://support.hp.com/in-en/drivers/selfservice/hp-easy-start/7376041

And, install HP smart app from here: https://support.hp.com/in-en/document/c04675142

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.