See https://github.com/FreeCAD/FreeCAD/issues/18170
and https://github.com/FreeCAD/FreeCAD/issues/18168

Index: src/Mod/Material/App/CMakeLists.txt
--- src/Mod/Material/App/CMakeLists.txt.orig
+++ src/Mod/Material/App/CMakeLists.txt
@@ -58,6 +58,7 @@ generate_from_xml(ModelPy)
 generate_from_xml(UUIDsPy)
 
 SET(Python_SRCS
+    Exceptions.cpp
     Exceptions.h
     Array2DPy.xml
     Array2DPyImp.cpp
