If broadcasting parent transaction of a ticket fails because it references unknown outputs, there is a good chance that waiting a few seconds will resolve the issue because the ancestor transactions will propagate through the network and reach the mempool of the local dcrd instance.
NOTE: Candidate for backporting to 1.3 release
If broadcasting parent transaction of a ticket fails because it references unknown outputs, there is a good chance that waiting a few seconds will resolve the issue because the ancestor transactions will propagate through the network and reach the mempool of the local dcrd instance.