Ubuntu 18.04 doesn't see the HP scanner

I have just finished a long install/uninstall session in order to solve similar scanning problem. I can not say this is the best approach but I can give a few points I hope this saves someone time.

• I have disabled cups auto adding of printers during this process, not sure this is important.

• I have installed an older version of HPLIP 3.17.11. Even if it says that is doesn't support Ubuntu 18.04, this version is working... at least for my printer.

• During installation, automatic is selected and I have opted out for HPLIP updates.

• After installation, I have installed hp-plugin with command

  hp-plugin -i 
  

• Scanner at this point started working if I start simple-scan as a root.

• Need for that was fixed by executing

  chmod 755 /var/lib/hp
  

For me that was all.

I had been using HP Deskjet 4535 MFP Scanning feature within Ubuntu 16.04. However after installing 18.04, it didn't worked, as mentioned by Tanama. (While I had fresh installed 18.04, my home directory was same as one I had used for 16.04.)

I verified that "hplip" package was installed during 18.04 stock installation, and tried simple-scan, sane-utils, hp-setup, hp-probe and so on. None of those attempts worked. Even Gimp -> Create -> xscanimage didn't helped.

Finally, following worked for me.

1. I installed hplip-gui package after going through this URL: https://websiteforstudents.com/installing-hp-printer-drivers-on-ubuntu-16-04-17-10-18-04-desktop/

2. Run Dash -> HPLIP Toolbox (HP Device Manager) and configured my device. I had used manual mode to detect device by explicitly providing static IP address I have assigned to my Wireless MFP. After that, use Actions tab within HP Device Manager, and select "Scan". It starts "simple-scan".

I had similar issue with Officejet 6700 All in One printer. After installing HPLIP and running "sudo apt install hplip-gui", issues are solved. Printing, scanning and fax are supported.

I just wanted to add that I had exactly the same experience (18.04 does not rcognize scanner HP3630). I installed simple scan in a minute and it works just fine

This worked for me in Ubuntu 21.04 and Ubuntu 21.10:

1. Install these packages:

   sudo apt install hplip hplip-gui libsane-hpaio
   

2. Run hp-setup

3. Choose "Network/Ethernet/Wireless", click "Show Advanced Options", and tick "Manual Discovery". Enter the IP address of the printer. (I found it couldn't find the printer automatically, but did add it once I entered the correct IP address.)

   

4. Click "Next" and finish the wizard.

It should now be possible to both print and scan.