Getting Celery task results using RPC backend
According to Celery documentation:
RPC Result Backend (RabbitMQ/QPid)
The RPC result backend (rpc://) is special as it doesn’t actuallystore the states, but rather sends them as messages. This is animportant difference as it means that a result can only be retrievedonce, and only by the client that initiated the task. Two differentprocesses can’t wait for the same result.
So using rpc:// isn't suitable for retrieving results later by another request.