I had this sort of problem on Debian 10, and found several things which together got scanning working for me on HP Color LaserJet Pro MFP M277dw. I hope the proceedure below is of help to someone else.
1. Fix the source for the gpg key to avoid the problem with the pgp.mit.edu server:
sudo cp -a /usr/share/hplip/base/validation.py /usr/share/hplip/base/validation.py.ORIG
vim /usr/share/hplip/base/validation.py
# replace pgp.mit.edu with pool.sks-keyservers.net on line 44
2. After getting the plugin to install using "hp-plugin" as a regular user and the root password when requested, the software still complained...
3. It seems that hplip expects the libraries in a different location than where they are getting installed:
I had this sort of problem on Debian 10, and found several things which together got scanning working for me on HP Color LaserJet Pro MFP M277dw. I hope the proceedure below is of help to someone else.
1. Fix the source for the gpg key to avoid the problem with the pgp.mit.edu server:
sudo cp -a /usr/share/ hplip/base/ validation. py /usr/share/ hplip/base/ validation. py.ORIG
vim /usr/share/ hplip/base/ validation. py
# replace pgp.mit.edu with pool.sks- keyservers. net on line 44
2. After getting the plugin to install using "hp-plugin" as a regular user and the root password when requested, the software still complained...
3. It seems that hplip expects the libraries in a different location than where they are getting installed:
find /usr/lib -name "*sane*" | grep hp2000S
sudo ln -s /usr/lib /usr/lib/ i386-linux- gnu x86_64- linux-gnu
sudo ln -s /usr/lib64 /usr/lib64/
(Based on https:/ /bugs.launchpad .net/hplip/ +bug/1818629)