I got some cups server error: "client-error-not-possible"
Here are some suggestions:
To be able to manage the cups printing jobs through web, you need to login first. Click on the "Administration" icon at the top of page http://localhost:631, it will prompt for user name and password.
This is also the place where you can cancel printing jobs that are hanging for some reason.
Then I noticed the printer was not active.
I already found out about this by giving this command: lpstat -t
printer HP_LaserJet_2100 uitgeschakeld sinds
On the cups webpage you can enable the printer again.
But also via terminal: lpadmin -p
Now the pinter is recongized in the HPLip Toolbox and accepts printing jobs, and gives no errors but nothing happens!!
Another solution was brought up: to install printconf.
When I had done that (sudo apt-get install printconf) I got the next error message: Unable to read printer database. Please ensure the "foomatic-db" package is installed properly.
I found the suggestion to see what drivers are available for the printer, using this command as a regular user:
foomatic-datafile -A | grep HP_LaserJet_2100
No output. Found out that installing gnome-cups-manager was sometimes an effective workaround; seems to be part of a normal install but was missing on my pc.
Recognized the printer right away. After that while printing with a gnome (Eye of Gnome) image viewer the image was printed alright. Pfff, that was easy.... no it wasn't. These are the kind of tribulations that put people off of Linux. Happily I found some many good things in linux that even printing in Windows is not a viable option anymore ;-)).