Hello,
After upgrading to 7.5.0, when trying to set Logstash up again, errors keep occurring relating to the "Failed to execute". Everything was working before the upgrade, but now it doesn't seem to like what is there... or maybe I am just being slow with this one.. likely!! 
So this is the error message that is being displayed when debugging -
[ERROR][logstash.agent ] Failed to execute action {:action=>LogStash::PipelineAction::Create/pipeline_id:main, :exception=>"LogStash::ConfigurationError", :message=>"Expected one of [ \\t\\r\\n], \"#\", \"input\", \"filter\", \"output\" at line 10, column 1 (byte 322)
Below is the pipelines.yml (The original one) -
- pipeline.id: main
path.config: "/path/to/logstash/conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-demo
path.config: "/path/to/logstash/tester-dir/demotester.conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-live
path.config: "/path/to/logstash/tester-dir/tester.conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-nonlive
path.config: "/path/to/logstash/tester-dir/nontester.conf.d/*.conf"
pipeline.workers: 1
Also below is a test with using the "config.string" element -
- pipeline.id: main
path.config: "/path/to/logstash/conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-demo
path.config: "/path/to/logstash/tester-dir/demotester.conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-live
path.config: "/path/to/logstash/tester-dir/tester.conf.d/*.conf"
pipeline.workers: 1
- pipeline.id: tester-nonlive
path.config: "/path/to/logstash/tester-dir/nontester.conf.d/*.conf"
pipeline.workers: 1
pipeline.batch.size: 1
config.string: "input { generator {} } filter { sleep { time => 1 } } output { stdout {} }"
Been having a look around and playing with the settings a little, with the adding of "pipeline.batch.size" and have tried with the "main" pipeline.id in the logstash.yml being commented out and when it was configured. But still with the same error.
Thank you in advance! 