diff --git a/DistUpgrade/DistUpgradeController.py b/DistUpgrade/DistUpgradeController.py
index b7dd0af7..dd9d171d 100644
--- a/DistUpgrade/DistUpgradeController.py
+++ b/DistUpgrade/DistUpgradeController.py
@@ -2700,18 +2700,84 @@ class DistUpgradeController(object):
 
         try:
             import dbus
+            import dbus.bus
 
+            # Root D-Bus bridge
+            bus_address = None
+            try:
+                uid_str = os.environ.get('SUDO_UID') or os.environ.get('PKEXEC_UID')
+                if uid_str:
+                    import subprocess
+                    # Find the PID of mate-session for this user
+                    pid = subprocess.check_output(["pgrep", "-u", uid_str, "-n", "mate-session"]).decode().strip()
+                    if pid:
+                        with open(f"/proc/{pid}/environ", "r") as f:
+                            for line in f.read().split('\0'):
+                                if line.startswith("DBUS_SESSION_BUS_ADDRESS="):
+                                    bus_address = line.split("=", 1)[1]
+                                    os.environ["DBUS_SESSION_BUS_ADDRESS"] = bus_address
+                                    logging.debug("D-Bus successfully bridged: " + bus_address)
+                                    break
+            except Exception as e:
+                logging.debug("Failed to create D-Bus bridge: " + str(e))
+
+            # Drop root privileges
             self._setNonRootEUID()
 
             # The org.freedesktop.ScreenSaver.Inhibit effect lasts only
             # as long as the dbus connection remains open. Once u-r-u
             # exits, the connection will be closed and screen inhibition
             # will be removed.
-            self._session_bus = dbus.SessionBus()
-            proxy = self._session_bus.get_object('org.freedesktop.ScreenSaver',
-                                                 '/org/freedesktop/ScreenSaver')
-            screensaver = dbus.Interface(proxy, dbus_interface='org.freedesktop.ScreenSaver')
-            screensaver.Inhibit('trisquel-release-upgrader', 'Upgrading Trisquel')
+            if bus_address:
+                self._session_bus = dbus.bus.BusConnection(bus_address)
+            else:
+                self._session_bus = dbus.SessionBus()
+
+            inhibited = False
+
+            # Attempt 1: Generic Freedesktop
+            try:
+                proxy = self._session_bus.get_object('org.freedesktop.ScreenSaver',
+                                                     '/org/freedesktop/ScreenSaver')
+                screensaver = dbus.Interface(proxy, dbus_interface='org.freedesktop.ScreenSaver')
+                screensaver.Inhibit('trisquel-release-upgrader', 'Upgrading System', timeout=2)
+                logging.debug('Freedesktop ScreenSaver inhibited')
+                inhibited = True
+            except Exception as e:
+                logging.debug('Freedesktop Inhibit failed: ' + str(e))
+
+            # Attempt 2: MATE ScreenSaver
+            try:
+                proxy_ss = self._session_bus.get_object('org.mate.ScreenSaver',
+                                                        '/org/mate/ScreenSaver')
+                screensaver_mate = dbus.Interface(proxy_ss, dbus_interface='org.mate.ScreenSaver')
+                screensaver_mate.Inhibit('trisquel-release-upgrader', 'Upgrading System')
+                logging.debug('MATE ScreenSaver successfully inhibited')
+                inhibited = True
+            except Exception as e:
+                logging.debug('Failed to inhibit MATE ScreenSaver: ' + str(e))
+
+            # Attempt 3: SessionManager - MATE, fallback to GNOME namespace
+            try:
+                try:
+                    proxy_sm = self._session_bus.get_object('org.mate.SessionManager',
+                                                            '/org/mate/SessionManager')
+                    session_mate = dbus.Interface(proxy_sm, dbus_interface='org.mate.SessionManager')
+                    session_mate.Inhibit('trisquel-release-upgrader', 0, 'Upgrading System', 8)
+                except Exception:
+                    # Fallback for MATE systems using legacy GNOME namespace
+                    proxy_sm = self._session_bus.get_object('org.gnome.SessionManager',
+                                                            '/org/gnome/SessionManager')
+                    session_mate = dbus.Interface(proxy_sm, dbus_interface='org.gnome.SessionManager')
+                    session_mate.Inhibit('trisquel-release-upgrader', 0, 'Upgrading System', 8)
+
+                logging.debug('SessionManager DPMS successfully inhibited')
+                inhibited = True
+            except Exception as e:
+                logging.debug('Failed to inhibit SessionManager DPMS: ' + str(e))
+
+            if not inhibited:
+                raise Exception("Neither Freedesktop, nor MATE, nor GNOME namespaces could be inhibited")
 
             summary = _("Lock screen disabled")
             message = _("Your lock screen has been "