As these are the first reports that we have seen of this error we will require some more information so that we can replicate and resolve the issue. Can you please provide the version of Octopus that you are using and the raw output from the task log in Octopus for this deployment task please?
As there are multiple responders on this thread the logs will not be private so I advise emailing them directly to us at support @ octopus dot com referencing this issue.
If the error is occurring prior to the deployment task running can you please provide screenshots of where the error is occurring?
I look forward to your response and resolving this issue as quickly as possible,
Just cross-check if you have two steps with same name. This issue will occur if you have two steps with same name. I have also faced the same issue and it got resolved once I renamed the step.