Hi,

Similar problem on Debian 10.5 buster (see below). I do not understand how to apply shivani1708's suggestion (python3-dbus is already installed and many python or python3 qt5 packages are already installed). 

Yours

MISSING DEPENDENCIES
--------------------
Following dependencies are not installed. HPLIP will not work if all REQUIRED dependencies are not installed and some of the HPLIP features will not work if OPTIONAL dependencies are not installed.
Package-Name         Component            Required/Optional   
pyqt5-dbus           gui_qt5              OPTIONAL            
pyqt4-dbus           gui_qt4              REQUIRED            
pyqt5                gui_qt5              REQUIRED            
Do you want to install these missing dependencies (y=yes*, n=no, q=quit) ? 


INSTALL MISSING REQUIRED DEPENDENCIES
-------------------------------------
note: Installation of dependencies requires an active internet connection.
warning: Missing REQUIRED dependency: pyqt4-dbus (PyQt 4 DBus - DBus Support for PyQt4)
warning: Missing REQUIRED dependency: pyqt5 (PyQt 5- Qt interface for Python (for Qt version 4.x))


INSTALL MISSING OPTIONAL DEPENDENCIES
-------------------------------------
note: Installation of dependencies requires an active internet connection.
warning: Missing OPTIONAL dependency for option 'gui_qt5': pyqt5-dbus (PyQt 5 DBus - DBus Support for PyQt5)


CHECKING FOR NETWORK CONNECTION
-------------------------------
Network connection present.


RUNNING PRE-PACKAGE COMMANDS
----------------------------
warning: An error occurred running 'su -c "dpkg --configure -a"'
su -c "dpkg --configure -a" (Pre-depend step 1)
su -c "apt-get install -f" (Pre-depend step 2)
su -c "apt-get update" (Pre-depend step 3)
OK


DEPENDENCY AND CONFLICT RESOLUTION
----------------------------------
Running 'su -c "apt-get install --force-yes -y python-qt4-dbus"'
Please wait, this may take several minutes...
Running 'su -c "apt-get install --force-yes -y gtk2-engines-pixbuf"'
Please wait, this may take several minutes...
Running 'su -c "apt-get install --force-yes -y python-pyqt5"'
Please wait, this may take several minutes...
Running 'su -c "apt-get install --force-yes -y python-dbus.mainloop.pyqt5"'
Please wait, this may take several minutes...
error: A required dependency 'pyqt4-dbus (PyQt 4 DBus - DBus Support for PyQt4)' is still missing.
error: A required dependency 'pyqt4 (PyQt 4- Qt interface for Python (for Qt version 4.x))' is still missing.


RUNNING POST-PACKAGE COMMANDS
-----------------------------
OK


RE-CHECKING DEPENDENCIES
------------------------
error: A required dependency 'pyqt4-dbus (PyQt 4 DBus - DBus Support for PyQt4)' is still missing.
error: A required dependency 'pyqt4 (PyQt 4- Qt interface for Python (for Qt version 4.x))' is still missing.
error: Installation cannot continue without these dependencies.
error: Please manually install this dependency and re-run this installer.

$ dpkg -l|grep python|grep qt5
ii  python-dbus.mainloop.pyqt5            5.11.3+dfsg-1+b3                    amd64        D-Bus Qt main loop support for Python 2
ii  python-pyqt5                          5.11.3+dfsg-1+b3                    amd64        Python 2 bindings for Qt5
ii  python3-pyqt5                         5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5
ii  python3-pyqt5.qtmultimedia            5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's Multimedia module
ii  python3-pyqt5.qtopengl                5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's OpenGL module
ii  python3-pyqt5.qtsvg                   5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's SVG module
ii  python3-pyqt5.qtwebchannel            5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's WebChannel module
ii  python3-pyqt5.qtwebengine             5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's WebEngine module
ii  python3-pyqt5.qtwebkit                5.11.3+dfsg-1+b3                    amd64        Python 3 bindings for Qt5's WebKit module