Receipts cannot be signed on dev because of a Trunion error. The request: http://sentry.dmz.phx1.mozilla.com/marketplace-dev/marketplace-dev/group/21693/ Exception in Trunion: HTTPConflict("nbf(not before) of receipt > exp(expires at) of signing cert") I think this is because the Trunion cert on dev has expired. It looks like this was used to generate the cert: https://github.com/mozilla/trunion/blob/master/scripts/certgen/apps/certgen.sh but I don't know if that needs to be run again or how it works to fix up a cert.
I used https://github.com/mozilla/trunion/blob/master/scripts/certifier.py script to generate a cert that expires in 2 years. Please verify.