Package: xdg-utils Followup-For: Bug #576829 FYI. Works for me:
user@debian:/tmp$ xdg-settings get default-web-browser firefox-esr.desktop user@debian:/tmp$ xdg-settings set default-web-browser chromium.desktop user@debian:/tmp$ xdg-settings get default-web-browser chromium.desktop user@debian:/tmp$ -- Package-specific info: Desktop environment: XDG_CURRENT_DESKTOP=MATE -- System Information: Debian Release: bullseye/sid APT prefers testing-debug APT policy: (500, 'testing-debug'), (500, 'unstable') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 5.2.0-3-amd64 (SMP w/32 CPU cores) Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled xdg-utils depends on no packages. Versions of packages xdg-utils recommends: ii libfile-mimeinfo-perl 0.29-1 ii libnet-dbus-perl 1.2.0-1 ii libx11-protocol-perl 0.56-7 ii x11-utils 7.7+4 ii x11-xserver-utils 7.7+8 xdg-utils suggests no packages. -- no debconf information