ACMEv2 staging new-order sometimes fails with "Error finalizing order"

@larryboymi How recently have you seen issues? The maybe-the-same-thing thread jmorahan linked to was fixed yesterday.

https://letsencrypt.status.io/pages/maintenance/55957a99e800baa4470002da/5abd11c975b2bd04e3626da1

(And probably fixed Tuesday in staging.)