Printer problems after installing Ubuntu 20.04

Try sudo hp-setup -i. At least for USB. That finally helped me with a HP LaserJet Pro P1102w.

If the printer was working for you with hplip before, just uninstall ippusbxd package:

sudo apt remove ippusbxd

The problem, at least in my case, was that ippusbxd was automatically creating a printer that was not working and was conflicting with my hplip printer.

1. install hplip gui as below

   sudo apt install hplip-gui
   

2. from hplip gui go to actions and then install required plugin.

And this fixed it for fr model HP LasetJet 1018

I have solved with the following steps, don't know if all are required, most likely only step 3 is the fix.

1. Removed and reinstalled some packages:

   sudo apt-get update
   sudo apt-get remove hplip cups-filters cups hplip-data system-config-printer-udev
   sudo apt-get install build-essential tix groff dc axel cups
   sudo apt-get install cups-filters unp system-config-printer-gnome
   

2. installed hplip from the hp's Developer Portal: https://developers.hp.com/hp-linux-imaging-and-printing/gethplip

   ver 3.20.5 claims to be compatible with 20.04 but in my case was not solving the issue:

3. Finally, changing permissions to the ppd file:

   sudo chmod 644 /etc/cups/ppd/HP_ENVY_4520_series_XXXXXX_.ppd 
   

   where (i suppose) XXXXXX should be part of the serial number of the printer

Now the printer works fine. It took me several days to achieve this result, the printer was working perfectly on 19.10, so I am a little disappointed of this issue.