[Django]-Django annotate Concat – Expression contains mixed types. You must set output_field

You must pass output_field to your db function, in your code you pass it to annotate.

queryset = Motocycle.objects.annotate(
    full_name=Concat(
        'title',
         Value(' '),
         F('engine_displacement'),
         Value(''),
         output_field=CharField(),
    ),
).all()