"message": "Reference: $.steps.connector-1.******[ in property: '*****' did not resolve to any value." (stub)

This message means that the JSON path you're using in the connector's input can't find any value associated with that JSON path -- it doesn't exist. Whenever you encounter that kind of error, inspect the JSON body to verify what is or isn't there. 

Example

In this workflow, the builder is using a JSON path to reference the 'content' field of the 'result' of the script-6 step:

​

Looking at this JSON path, I would expect to go to the output of script-6 step and find a 'content' field inside the 'result' field.

The output of the script-6 step looks like this, however:

{
 "result": {
  "isValid": false
 },
 "console": []
}

There is a 'result' field but no 'content' field. 

There's a similar error on another execution step:

{
 "message": "Reference: $.steps.script-6.result.content in property: 'body.raw.product.media_gallery_entries[].content.base64_encoded_data' did not resolve to any value."
}

Anytime you see the message, "did not resolve to any value," you'll need to check that the JSON path is referencing something that actually exists.

If you want to accommodate potentially non-existent values in your workflow, you can always set your JSON paths to have 'fallback values'-- you can read about how to set those up here: Fallback Values.