diff --git a/src/blenderbim/blenderbim/bim/module/model/product.py b/src/blenderbim/blenderbim/bim/module/model/product.py
index 9b5d3e93d4..bfb7349391 100644
--- a/src/blenderbim/blenderbim/bim/module/model/product.py
+++ b/src/blenderbim/blenderbim/bim/module/model/product.py
@@ -6,6 +6,7 @@ import ifcopenshell.util.representation
 from . import wall, slab
 from blenderbim.bim.ifc import IfcStore
 from ifcopenshell.api.pset.data import Data as PsetData
+from mathutils import Vector
 
 
 class AddTypeInstance(bpy.types.Operator):
diff --git a/src/blenderbim/blenderbim/bim/module/model/slab.py b/src/blenderbim/blenderbim/bim/module/model/slab.py
index 22a7f241b5..ba7ceb2997 100644
--- a/src/blenderbim/blenderbim/bim/module/model/slab.py
+++ b/src/blenderbim/blenderbim/bim/module/model/slab.py
@@ -150,7 +150,7 @@ class DumbSlabPlaner:
     def regenerate_from_type(self, usecase_path, ifc_file, settings):
         self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(ifc_file)
         new_material = ifcopenshell.util.element.get_material(settings["relating_type"])
-        if not new_material.is_a("IfcMaterialLayerSet"):
+        if not new_material or not new_material.is_a("IfcMaterialLayerSet"):
             return
         new_thickness = sum([l.LayerThickness for l in new_material.MaterialLayers])
         self.change_thickness(settings["related_object"], new_thickness)
diff --git a/src/blenderbim/blenderbim/bim/module/model/wall.py b/src/blenderbim/blenderbim/bim/module/model/wall.py
index b235f77441..0a1963185a 100644
--- a/src/blenderbim/blenderbim/bim/module/model/wall.py
+++ b/src/blenderbim/blenderbim/bim/module/model/wall.py
@@ -819,7 +819,7 @@ class DumbWallPlaner:
     def regenerate_from_type(self, usecase_path, ifc_file, settings):
         self.unit_scale = ifcopenshell.util.unit.calculate_unit_scale(ifc_file)
         new_material = ifcopenshell.util.element.get_material(settings["relating_type"])
-        if not new_material.is_a("IfcMaterialLayerSet"):
+        if not new_material or not new_material.is_a("IfcMaterialLayerSet"):
             return
         new_thickness = sum([l.LayerThickness for l in new_material.MaterialLayers])
         self.change_thickness(settings["related_object"], new_thickness)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/type/assign_type.py b/src/ifcopenshell-python/ifcopenshell/api/type/assign_type.py
index d11fb8f3ae..e79319377e 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/type/assign_type.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/type/assign_type.py
@@ -84,6 +84,8 @@ class Usecase:
 
     def map_material_usages(self):
         type_material = ifcopenshell.util.element.get_material(self.settings["relating_type"])
+        if not type_material:
+            return
         if type_material.is_a("IfcMaterialLayerSet"):
             ifcopenshell.api.run(
                 "material.assign_material",