Why Can't I Assign an Approval Step to a Queue for a Custom Object Approval Process in salesforce?

Hi Deepak,

You can assign approvals on a detail object to queues, but only if you create a queue that can own the master object. This may not be possible if the master object cannot be owned by a queue.

These approval processes on the detail object that reference queues for the master object cannot be deployed via the metadata API, but can be created/modified through the standard UI. (you can deploy them with the assignment to a named user, and then switch it to the queue through the UI).

I've also heard of people working around the issue in the following way:

Creating the detail object without the master detail relationship
Creating queues for that object
Creating the approval process with the queues referenced
Adding the master detail relationship to the object.
You may want to try this, but it could be that it is no longer possible or unsupported by salesforce, it's certainly an ugly workaround.

Thanks