Ok. As i see many people dosen’t underestand so here i go.
Open physics asset of your mannequin or other rig and you will see this:
I already did it so y have root body, but you dont.
To add it go here into this thing and select->Show All Bones
It’s Ue5 btw, but in ue4 it looks similar. After clicking there it will look like this:
Next - click to the … hm to the root bone right mouse button->Add Sphere
It will appear in the root of character here:
Ok, now we need to select this body and set it’s Physics Type to kinematic at the right panel:
Why do we need this body anyway? Well… if you have to make ragdoll, then you, probably, attaching your character to something(capsule?) during ragdoll state. But since there is No kinematic bodies by default - engine will throw you error. Each attachable rig should have kinematic body on it.
But we are not done yet.
In the bottom left screen you can see body constraints tab, here:
I already set it so in your case it will have only one body ant it’s the root itself.
We need to attach Pelvis to the Root. Click at the root … item with right mouse->Constraints-> select Pelvis bone
After douing so during ragdoll your character will look like this:
Why? Because our pelvis locked by root.
We need to free it. So go to created Root body and click on the constraint Root->Pelvis in there:
In Right details tab you can find this:
Linear Limits. They are locked by default but you can set them to Free! Do so.
And here we go. All works, no warnings.
Don’t worry about root body collision with the ground. Just note Not to set “Ragdoll” type of physics to the Whole character mesh. Enable ragdoll this way instead:
In this case kinematically simulated root bone won’t affect world transforms. Also you can set in the constraints some limits yourself if need so. Ok, hope my post helps someone.