Multiple root bone error (from blender to UE4)

Hello everyone,

I have run into a new problem.
I tried to import a skeletal mesh (FBX file) that I made in blender.
But when I try to do that it gives me a “multiple root bone error”:

293629-multiple-root-bones-problem.png

I tried to search on this problem and found a lot of forum post’s with other people with this problem.
And most times people had some unparented bones in there skeletons but I’ve checkt my blender file multiple times now but as far as I see all my bones are parented. (except for the root bone of course)
So I don’t get what the problem is.
Normally I would rig my character again from scratch but in this case I hope there is a other solution since my character contains 306 bones… :expressionless:

The engine also gives an where it says that not all my bones have unique name but I’m pretty sure they all have a unique name.
I also tried to rename the bone that according to engine has no unique name but when I do that it will go to another bone and says that that bone don’t have a unique name.

So does anyone know a solution to this problem?
Download link to my blender file: https://we.tl/t-89QGYB2eq9

Thx in advance for reading and thinking!
Grover

I don’t know but perhaps these image may help to tackle the problem:

(Bone hierarchy)

There seems to be a bone with the same name. try lokjking through your bones and find 2 with the name “RH_wijvinger”