Often times, if you are using Child Flows and but you see some unexpected while Saving your parent Flows upon adding a Child Flow, which usually look like the below
Assuming, you are aware of using Child Flows and that they can only be created inside a Solution. (Of course, that’s why you could encounter this issue since you’re able to set a Child Flow already 
)
Reason Issue
Let’s say…
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ChildFlowUnsupportedForInvokerConnections error while using Child Flows [SOLVED] | Power Automate – D365 Demystified
Here’s what to do when you encounter an issue saving a parent Flow while using Child Flows
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