How to Upgrade Debian 9 and Fix Common GNOME3 & Network‑Manager Issues

Preparation before upgrading

Back up the following files and directories before starting the upgrade: /usr/share/gnome-shell/theme/gnome-shell.css (needed for GNOME 3 optimizations after the upgrade) /etc/apt (easier to restore software source settings later) /etc (configuration files for services such as dnsmasq, tftp, apache, vsftpd, etc.)

New Network‑Manager issues and solutions

2.1 Network‑Manager device‑management

Debian 9 ships Network‑Manager version 1.6.2-3. The old method of marking devices as unmanaged no longer works. Use the following command to set a device to unmanaged mode: nmcli device set {interface_name} managed no For example: nmcli device set eth0 managed no To revert to managed mode, replace no with yes. Check the current status with:

nmcli device status

2.2 Wi‑Fi MAC‑address randomization

Since Network‑Manager 1.4.0, MAC randomization is enabled by default, causing the MAC address of a USB Wi‑Fi adapter to change on each plug‑in. To disable this feature, edit /etc/NetworkManager/NetworkManager.conf and add a [device] section with the appropriate parameters, then restart the service:

systemctl restart NetworkManager.service

2.3 Touch‑pad tap disabled

After the upgrade, tap‑to‑click may stop working. Verify the current settings: synclient | grep TapButton If the values are 0, edit /usr/share/X11/xorg.conf.d/70-synaptics.conf and add the necessary parameters after the existing no section (see the screenshot). Save the file and restart the GNOME 3 desktop; tap and two‑finger tap should be restored.

GNOME 3 issues and solutions

3.1 Adjusting the window title bar

Older Debian versions allowed modifying the title bar height via a sed command on /usr/share/themes/Adwaita/metacity-1/metacity-theme-3.xml. In Debian 9 this file no longer exists. Instead, create or edit ~/.config/gtk-3.0/gtk.css and add the required CSS (see screenshot). Press ALT+F2, type r, and restart the desktop to see the reduced title bar height.

3.2 Top‑bar (task bar) optimization

In Debian 8 you could edit /usr/share/gnome-shell/theme/gnome-shell.css to change the height and background color of the top bar. In Debian 9 the file is missing. Create the directory /usr/share/themes/Adwaita/gnome-shell, place a copy of the old gnome-shell.css there, and then select the Adwaita theme. Restart the desktop service to apply the changes.

Useful GNOME 3 extensions and tools

The following extensions improve the GNOME 3 experience. Installation methods are shown in the accompanying screenshots.

NetSpeed – displays real‑time network traffic on the top bar.

dash‑to‑dock – enhances the dock with transparency, auto‑hide, and other features.

workspaces‑to‑dock – provides mouse‑triggered workspace switching.

CoverflowAltTab – adds a 3‑D visual switcher for open windows.

Pomodoro – integrates a customizable Pomodoro timer.

Docky – adds a dock at the bottom of the screen for easy application management.

Guake – a drop‑down terminal invoked with F12 (or a custom shortcut).

screen – a terminal multiplexer supporting split screens.

These extensions can be downloaded from the GNOME extensions website or its GitHub mirrors.