To resolve the error, you can follow the following steps. Troubleshooting a printer involves some standard procedures. Perform the troubleshooting steps given below to resolve the scanning issue.

Uninstall the printer software

1. In Windows, open the Programs and Features option.
2. Choose your HP Officejet Pro 8720 printer model from the list of printers displayed.
3. Click Uninstall drivers.
4. Go to the Printers and Scanners option and search for your printer model.
5. Right-click on your printer model and select Remove Device.
6. Press Windows key and R key at the same time to open the run command.
7. Enter printui.exe /s and click OK.
8. Search for your HP printer drivers and select Remove drivers. Click Apply Changes and close the tab.

Update the new full feature printer drivers

1) Download the software and drivers required for your printer model.
2) Run the Setup file downloaded from the Downloads folder.
3) Follow the on-screen instructions to install the full feature drivers for your printer.
4) Install ink cartridges in the ink cartridge slot and load papers into the paper input tray.
5) Open a document or photo and try printing a sample page.
6) If the error persists, move on to the next troubleshooting step.

Run the HP Print and Scan Doctor

1. Download the HP Print and Scan Doctor from the web.
2. Follow the on-screen commands to complete the installation.
3. Open the HP Print, and Scan Doctor tool click Start on the Welcome screen.
4. View the list of available printers and choose your printer in the list.
5. If your printer model is not listed, click My Product is not listed and retry.
6. Choose Fix Scanner problem and examine the test results.
7. If you notice a wrench icon, it indicates that HP Print and Scan Doctor found a problem and fixed it.
8. If you see an exclamation, it means that the test failed.
9. If you notice a tick icon, it indicates the printer passed the test.