Your problem was that the printer´s firmware did not get installed properly with the hp-plugin utility. Downloading and verifying the digital signature worked, but the graphical user interface of hp-plugin had a bad interference with ibus. ibus is an input method infrastructure for non-latin-character languages. The firmware installation worked when you used the version of hp-plugin without graphical user interface ("hp-plugin -i").
Can anyone at HP check this? Note that the user works under Russian locale, probably under US English locale this bug will not appear.
Your problem was that the printer´s firmware did not get installed properly with the hp-plugin utility. Downloading and verifying the digital signature worked, but the graphical user interface of hp-plugin had a bad interference with ibus. ibus is an input method infrastructure for non-latin-character languages. The firmware installation worked when you used the version of hp-plugin without graphical user interface ("hp-plugin -i").
Can anyone at HP check this? Note that the user works under Russian locale, probably under US English locale this bug will not appear.