  This erratum corrects the proof given in \cite{E1,E2} about the existence of
$ 3D $ Skyrmions. This is done by changing the arguments of the proof while
remaining in the same framework of concentration-compactness. Note however that
the use of this method is here different of most of what has been done with it
so far. In that sense, this new proof has some interest by itself. The proof
given here is self-contained. I thank F. Lin and Y. Yang for having pointed out
to me that there were gaps in my proofs.
