The specified keyring may be incorrect or out of date

[Nathan Teodosio]

--->
% mk-sbuild --arch=amd64 --distro=ubuntu bionic
I: Retrieving InRelease
I: Checking Release signature
E: Release signed by unknown key (key id 3B4FE6ACC0B21F32)
   The specified keyring /usr/share/keyrings/ubuntu-archive-removed-keys.gpg may be incorrect or out of date.
   You can find the latest Debian release key at https://ftp-master.debian.org/keys.html
<---

Resolved by deleting said key-ring and retrying the command.

Also note the failed command nonetheless creates a mostly empty /var/lib/schroot/chroots/bionic-amd64/ so trying mk-sbuild again fails without removing the directory first.

% sbuild --version
sbuild (Debian sbuild) 0.85.10 (30 May 2024)
% lsb_release -r
Release: 24.10