diff --git a/cura/CrashHandler.py b/cura/CrashHandler.py
index ad80d286c3..c6f94f0a80 100644
--- a/cura/CrashHandler.py
+++ b/cura/CrashHandler.py
@@ -75,7 +75,6 @@ class CrashHandler:
 
     ##  Creates a modal dialog.
     def _createDialog(self):
-        self.dialog = QDialog()
         self.dialog.setMinimumWidth(640)
         self.dialog.setMinimumHeight(640)
         self.dialog.setWindowTitle(catalog.i18nc("@title:window", "Crash Report"))
diff --git a/cura/QualityManager.py b/cura/QualityManager.py
index 0312c50daf..abd14fa841 100644
--- a/cura/QualityManager.py
+++ b/cura/QualityManager.py
@@ -198,13 +198,6 @@ class QualityManager:
             else:
                 materials.append(global_container_stack.material)
 
-        # if extruder_stacks:
-        #     # Multi-extruder machine detected.
-        #     materials = [stack.material for stack in extruder_stacks]
-        # else:
-        #     # Machine with one extruder.
-        #     materials = [global_container_stack.material]
-
         quality_types = self.findAllQualityTypesForMachineAndMaterials(global_machine_definition, materials)
 
         # Map the list of quality_types to InstanceContainers
diff --git a/cura/Settings/ProfilesModel.py b/cura/Settings/ProfilesModel.py
index 2981873de8..6353d3ce84 100644
--- a/cura/Settings/ProfilesModel.py
+++ b/cura/Settings/ProfilesModel.py
@@ -166,7 +166,7 @@ class ProfilesModel(InstanceContainersModel):
         for item in containers:
             profile = container_registry.findContainers(id = item["id"])
 
-            # when the profile is not supported
+            # When for some reason there is no profile container in the registry
             if not profile:
                 self._setItemLayerHeight(item, "", "")
                 item["available"] = False
@@ -175,7 +175,7 @@ class ProfilesModel(InstanceContainersModel):
 
             profile = profile[0]
 
-            # empty qualities should show in the list (they are "Not Supported" profiles)
+            # When there is a profile but it's an empty quality should. It's shown in the list (they are "Not Supported" profiles)
             if profile.getId() == "empty_quality":
                 self._setItemLayerHeight(item, "", "")
                 item["available"] = True