The optimality conjecture for crepant resolutions of log-terminal singularities

Let $Y$ be an irreducible $\mathbb{Q}$-Gorenstein variety, and let

$$\pi\colon\mathcal{X}\to Y$$

be a crepant resolution such that $\mathcal{X}$ has affine diagonal. Optimality conjecture for crepant resolutions. Then $Y$ has log-terminal singularities.

The conjecture asserts that the existence theorem for crepant resolutions by smooth Artin stacks cannot be extended beyond the log-terminal case under the stated affine-diagonal hypothesis. The source presents it as reasonable in light of the convergence criterion for the relevant motivic integral and the motivic change-of-variables formula; its resolution status is not specified.