HPLIP Driver install fails on Ubuntu 20.04

The debug option worked for me, but as a second step I had to type "cont" and press Return to get the depicted process to run.

I had the same problem and I can confirm that with the debug option the scanner plugin gets installed.

pdb3 /usr/share/hplip/plugin.py  -i -g

I am currently running Ubuntu 20.04. I have a HP LaserJet Pro MFP M226dw. It is a multi-function printer supporting both printing and scanning. I similarly had difficulty with scanning. Fortunately, I was able to get printing work earlier.

I already had hplip-3.21.2.run installed in my system. I believed that the problem was with the scanner plugin. The automatic command to download the plugin shown above did not work. So, I manually downloaded the latest script from the HPLip website.

Then, I ran this command to install the plugin:

sh hplip-3.21.2-plugin.run

That fixed the scanner for me. Now, I am able to scan without any issues.