Problem
When I try to cancel the parent-child relationship, I get a message saying “Loop in parents”…
Cause
Trying to create a double parent-child relationship
This time, I will introduce how to deal with “Loop in parents” in Blender.
Error “Loop in parents”
In Blender 2.78, “Parent is cycling.”
Cause: Trying to create a double parent-child relationship

If you select one of the following when canceling the parent-child relationship after an armature has been created, an error will occur.
- Armature deformation
- in an empty group
- with automatic weights
- with envelope weights
How to break the parent-child relationship of an armature
- [Object mode]
- Select Armature → Object.
- [Object context menu] → [Parent] → [Clear parent-child relationship].

That’s it!
Lastly
I’m sure he slipped his hands to cancel the parent-child relationship after a long time. ← (self)
Operating Environment
- Windows 10 Pro 1909
- Blender 2.79, 2.83 Maya Config Addon For Blender 2.8, 2.90