The "No Available Workers" section of the troubleshooting doc  is out of date with a change that was made in 2.5.1. With 2.5.1 there is no way the user will encounter this exception.
Proposal: This section should be reworked, but left mostly the same. With 2.5.1 if the user does not have pulp_celerybeat, pulp_workers, or pulp_resource_manager setup correctly their tasks will be created, but will stall at the waiting state. This section should no longer talk about the NoAvailableWorkers section and instead talk about tasks stalling.
PR available at: https://github.com/pulp/pulp/pull/1239
Merged to 2.5-dev -> master
fixed in pulp 2.6.0-0.2.beta
Moved to https://pulp.plan.io/issues/569