Many thanks @gduperrey

I disable Dell repo.

@olivierlambert, I have a dell repo for OMSA.

I tried this :

yum install --setopt=protected_multilib=false --skip-broken libcom_err-1.47.0-1.1.xcpng8.2.x86_64

and it is running.

I have this error message when I tried to update version of my XCP-NG installation :

Error:  Multilib version problems found. This often means that the root
       cause is something else and multilib version checking is just
       pointing out that there is a problem. Eg.:

         1. You have an upgrade for libcom_err which is missing some
            dependency that another package requires. Yum is trying to
            solve this by installing an older version of libcom_err of the
            different architecture. If you exclude the bad architecture
            yum will tell you what the root cause is (which package
            requires what). You can try redoing the upgrade with
            --exclude libcom_err.otherarch ... this should give you an error
            message showing the root cause of the problem.

         2. You have multiple architectures of libcom_err installed, but
            yum can only see an upgrade for one of those architectures.
            If you don't want/need both architectures anymore then you
            can remove the one with the missing update and everything
            will work.

         3. You have duplicate versions of libcom_err installed already.
            You can use "yum check" to get yum show these errors.

       ...you can also use --setopt=protected_multilib=false to remove
       this checking, however this is almost never the correct thing to
       do as something else is very likely to go wrong (often causing
       much more problems).

       Protected multilib versions: libcom_err-1.47.0-1.1.xcpng8.2.x86_64 != libcom_err-1.42.9-19.el7.i686