Hello everyone,
For some days, I try to upload an armatured 3D model into Mixamo, but it’s saying always the same thing: “The hierarchy is not consistent: the path from the root node to the end of each limb should be unique!”
After that, I’ve tried many things to resolve it, but I couldn’t, for now (This is a 3D model of Resident Evil 4.)
I’ve already been on some websites to search for help, but nothing useful.
Any advices are welcome, thank you in advance 
Delete the skeleton that the character is rigged to.
Simple, re-upload the model and use their auto-rigger.
Thank you for your answer, I’ll do that
I’ll just lose the mouth bones.
Yes you should lose all bones. You more than likely will have to paint skin weights also. Its easier to retarget an animation in something like Maya Lt. If thats truly what you need to do. While keeping your character intact. Then you can have character interactions like blinking for example. You can also layer, and retarget them in unreal. Using a mixamo only character is actually a good bit of work. I rig my characters to UE4 skeleton. All of them. If I need a facial rig. Than I parent it to the UE4 skeleton. As there is a whole lot more content already blended in ue4.
Alright, finally, I modified the mixamo skeleton under Blender 2.78, to add some mouth bones then edit the model so it can open and close the mouth, what a pain …