My HP Scanjet was working using the old drivers in OS 10.12.4 until I updated to HP Easy Scan. Now when attempting to use "Easy Scan", I hear communication between the computer and the scanner but I get the message,
"HP Scanjet 5590 is currently unavailable. Ensure your device is powered on, check the connection, and ensure your network is functioning properly. If these conditions are correct, restart the device and try scanning again."
Of course I do ALL of the above suggestions plus rebooting the iMac. No luck. HP is to be chastised for putting out bad software and MUST update its failed "Easy Scan."