It looks like you did not pass 'task_name' to the execution command (you didn't add the workflow you tried and you execution command).

I am adding an example of how to use such workflow via cli.

Example:

workflow:

---
version: '2.0'

my_reverse_wf:
  type: reverse

  tasks:
    first:
      action: std.noop
    second:
      action: std.noop
      requires: [first]

inputs.json:

{}

params.json:

{"task_name": "second"}

execution command:

mistral execution-create my_reverse_wf inputs.json params.json