Erratum to: "The minimal exact crossed product"

We point out some mistakes in our paper [ibid. 23, 2043–2077 (2018; Zbl 1430.46050)]. The most severe one is a gap in our proof that the smallest exact crossed product functor, as constructed in [loc. cit.], is automatically Morita compatible. We were not able to close this gap so far. So, at this time, we cannot conclude that the C^* -group algebra C_{\epsilon_{M}}^*(G)=\mathbb{C}\rtimes_{\epsilon_{M}} G corresponding to the smallest exact Morita compatible crossed-product functor \rtimes_{\epsilon_{M}} is equal to the reduced group C^* -algebra C_r^*(G) .