@sjw @Terry @colonelj @p @mint Most likely entry isn't removed from oban federator_outgoing queue. Purely software errors might get recorded in errors column, that should be easiest to check first, if not, enabling debug logs, triggering/waiting for delivery attempt and then sifting through many megabytes of output would be required. Postgres logs at the same moment might also be helpful. Could be conflicting lock, transaction getting rolled back due to software error or some database error. Either way, combined output is likely to contain some hints.

Further speculations include runtime cache(s) not getting evicted, lingering oban workers from restarts/reloads without terminating main process. If issue stops reproducing after clean instance restart, could be the case, but locating such issues is ought to be involved and interactive process.

Could also be synchronization issue, if multiple workers somehow are getting the same task, but thats nearing improbability, it's not that difficult to implement row-locking postgres queue correctly to doubt oban implementation before other options are exhausted.