diff --git a/cura/Settings/MachineManager.py b/cura/Settings/MachineManager.py
index dec433e8f8..35f3268cce 100755
--- a/cura/Settings/MachineManager.py
+++ b/cura/Settings/MachineManager.py
@@ -1322,7 +1322,8 @@ class MachineManager(QObject):
     #   changed.
     #   \param position The extruder stack to update. If provided with None, all
     #   extruder stacks will be updated.
-    def updateMaterialWithVariant(self, position: Optional[str]) -> None:
+    @pyqtSlot()
+    def updateMaterialWithVariant(self, position: Optional[str] = None) -> None:
         if self._global_container_stack is None:
             return
         if position is None:
@@ -1353,10 +1354,9 @@ class MachineManager(QObject):
                 self._setMaterial(position_item, new_material)
             else:
                 # The current material is not available, find the preferred one.
-                if position is not None:
-                    approximate_material_diameter = int(self._global_container_stack.extruderList[int(position_item)].getApproximateMaterialDiameter())
-                    material_node = nozzle_node.preferredMaterial(approximate_material_diameter)
-                    self._setMaterial(position_item, material_node)
+                approximate_material_diameter = int(self._global_container_stack.extruderList[int(position_item)].getApproximateMaterialDiameter())
+                material_node = nozzle_node.preferredMaterial(approximate_material_diameter)
+                self._setMaterial(position_item, material_node)
 
     ##  Given a printer definition name, select the right machine instance. In case it doesn't exist, create a new
     #   instance with the same network key.
diff --git a/resources/qml/Preferences/Materials/MaterialsView.qml b/resources/qml/Preferences/Materials/MaterialsView.qml
index 6d5a8119c5..8a5ec79d53 100644
--- a/resources/qml/Preferences/Materials/MaterialsView.qml
+++ b/resources/qml/Preferences/Materials/MaterialsView.qml
@@ -111,6 +111,8 @@ TabView
                     {
                         base.setMetaDataEntry("approximate_diameter", old_approximate_diameter_value, getApproximateDiameter(new_diameter_value).toString());
                         base.setMetaDataEntry("properties/diameter", properties.diameter, new_diameter_value);
+                        // CURA-6868 Make sure to update the extruder to user a diameter-compatible material.
+                        Cura.MachineManager.updateMaterialWithVariant()
                         base.resetSelectedMaterial()
                     }