  Since curved dg algebras, and modules over them, have differentials whose
square is not zero, these objects have no cohomology, and there is no classical
derived category. For different purposes, different notions of "derived"
categories have been introduced in the literature. In this note, we show that
for some concrete curved dg algebras, these derived categories vanish. This
happens for example for the initial curved dg algebra whose module category is
the category of precomplexes, and for certain deformations of dg algebras.
