This article is part of the Working with Power Automate Child Flows series and of the larger Working with Power Automate series I am writing on my experiences working with the Power Automate, which is part of the Power Platform from Microsoft. I also have a related series of articles on Power Automate with Microsoft Dynamics 365 BC.
I did some work creating a number of Power Automate flows for a colleague to use in a demo to a client. Part way through creating the flows, I started having problems with one of the flows which called a child flow; the parent failed every time it tried to call the child: