The potential reasons are as follows:-
Reason 1:
If your pipeline is in the SCHEDULED state and one or more tasks
appear stuck in the WAITING_FOR_RUNNER state, ensure that you set a
valid value for either the runsOn or workerGroup fields for those
tasks. If both values are empty or missing, the task cannot start
because there is no association between the task and a worker to
perform the tasks. In this situation, you've defined work but haven't
defined what computer will do that work. If applicable, verify that
the workerGroup value assigned to the pipeline component is exactly
the same name and case as the workerGroup value that you configured
for Task Runner.
Reason 2:-
Another potential cause of this problem is that the endpoint and
access key provided to Task Runner is not the same as the AWS Data
Pipeline console or the computer where the AWS Data Pipeline CLI tools
are installed. You might have created new pipelines with no visible
errors, but Task Runner polls the wrong location due to the difference
in credentials, or polls the correct location with insufficient
permissions to identify and run the work specified by the pipeline
definition.
