I decided to upgrade 6.7 to 6.8 on my VM but hit an issue with yum:

Error: Package: gcc-gfortran-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: gcc = 4.4.7-16.el6

           Removing: gcc-4.4.7-16.el6.x86_64 (@clearos-core)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-16.el6

           Updated By: gcc-4.4.7-17.el6.x86_64 (clearos-updates)

               gcc = 4.4.7-17.el6

               gcc = 4.4.4-15.el6

           Available: gcc-4.4.7-11.el6.x86_64 (clearos)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-11.el6

Error: Package: gcc-gnat-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: gcc = 4.4.7-16.el6

           Removing: gcc-4.4.7-16.el6.x86_64 (@clearos-core)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-16.el6

           Updated By: gcc-4.4.7-17.el6.x86_64 (clearos-updates)

               gcc = 4.4.7-17.el6

               gcc = 4.4.4-15.el6

           Available: gcc-4.4.7-11.el6.x86_64 (clearos)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-11.el6

Error: Package: rpm-build-4.8.0-47.el6.x86_64 (@clearos-core)

           Requires: rpm = 4.8.0-47.el6

           Removing: rpm-4.8.0-47.el6.x86_64 (@clearos-core)

               rpm = 4.8.0-47.el6

           Updated By: rpm-4.8.0-55.el6.x86_64 (clearos-updates)

               rpm = 4.8.0-55.el6

           Available: rpm-4.8.0-38.el6_6.x86_64 (clearos)

               rpm = 4.8.0-38.el6_6

Error: Package: glibc-2.12-1.166.el6_7.7.i686 (clearos-centos-updates)

           Requires: glibc-common = 2.12-1.166.el6_7.7

           Removing: glibc-common-2.12-1.166.el6_7.7.x86_64 (@clearos-centos-updates)

               glibc-common = 2.12-1.166.el6_7.7

           Updated By: glibc-common-2.12-1.192.el6.x86_64 (clearos-updates)

               glibc-common = 2.12-1.192.el6

           Available: glibc-common-2.12-1.149.el6_6.5.x86_64 (clearos)

               glibc-common = 2.12-1.149.el6_6.5

           Available: glibc-common-2.12-1.166.el6.x86_64 (clearos-centos)

               glibc-common = 2.12-1.166.el6

           Available: glibc-common-2.12-1.166.el6_7.1.x86_64 (clearos-centos-updates)

               glibc-common = 2.12-1.166.el6_7.1

           Available: glibc-common-2.12-1.166.el6_7.3.x86_64 (clearos-centos-updates)

               glibc-common = 2.12-1.166.el6_7.3

Error: Package: python-magic-5.04-21.el6.x86_64 (@clearos-core)

           Requires: file = 5.04-21.el6

           Removing: file-5.04-21.el6.x86_64 (@clearos)

               file = 5.04-21.el6

           Updated By: file-5.04-30.el6.x86_64 (clearos-updates)

               file = 5.04-30.el6

Error: Package: elfutils-0.161-3.el6.x86_64 (@clearos-core)

           Requires: elfutils-libelf(x86-64) = 0.161-3.el6

           Removing: elfutils-libelf-0.161-3.el6.x86_64 (@clearos-core)

               elfutils-libelf(x86-64) = 0.161-3.el6

           Updated By: elfutils-libelf-0.164-2.el6.x86_64 (clearos-updates)

               elfutils-libelf(x86-64) = 0.164-2.el6

           Available: elfutils-libelf-0.158-3.2.el6.x86_64 (clearos)

               elfutils-libelf(x86-64) = 0.158-3.2.el6

Error: Package: elfutils-0.161-3.el6.x86_64 (@clearos-core)

           Requires: elfutils-libs(x86-64) = 0.161-3.el6

           Removing: elfutils-libs-0.161-3.el6.x86_64 (@clearos-core)

               elfutils-libs(x86-64) = 0.161-3.el6

           Updated By: elfutils-libs-0.164-2.el6.x86_64 (clearos-updates)

               elfutils-libs(x86-64) = 0.164-2.el6

Error: Package: libstdc++-devel-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: libstdc++(x86-64) = 4.4.7-16.el6

           Removing: libstdc++-4.4.7-16.el6.x86_64 (@clearos-core)

               libstdc++(x86-64) = 4.4.7-16.el6

           Updated By: libstdc++-4.4.7-17.el6.x86_64 (clearos-updates)

               libstdc++(x86-64) = 4.4.7-17.el6

           Available: libstdc++-4.4.7-11.el6.x86_64 (clearos)

               libstdc++(x86-64) = 4.4.7-11.el6

Error: Package: gcc-objc-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: gcc = 4.4.7-16.el6

           Removing: gcc-4.4.7-16.el6.x86_64 (@clearos-core)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-16.el6

           Updated By: gcc-4.4.7-17.el6.x86_64 (clearos-updates)

               gcc = 4.4.7-17.el6

               gcc = 4.4.4-15.el6

           Available: gcc-4.4.7-11.el6.x86_64 (clearos)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-11.el6

Error: Package: gcc-java-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: gcc = 4.4.7-16.el6

           Removing: gcc-4.4.7-16.el6.x86_64 (@clearos-core)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-16.el6

           Updated By: gcc-4.4.7-17.el6.x86_64 (clearos-updates)

               gcc = 4.4.7-17.el6

               gcc = 4.4.4-15.el6

           Available: gcc-4.4.7-11.el6.x86_64 (clearos)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-11.el6

Error: Package: gcc-c++-4.4.7-16.el6.x86_64 (@clearos-core)

           Requires: gcc = 4.4.7-16.el6

           Removing: gcc-4.4.7-16.el6.x86_64 (@clearos-core)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-16.el6

           Updated By: gcc-4.4.7-17.el6.x86_64 (clearos-updates)

               gcc = 4.4.7-17.el6

               gcc = 4.4.4-15.el6

           Available: gcc-4.4.7-11.el6.x86_64 (clearos)

               gcc = 4.4.4-15.el6

               gcc = 4.4.7-11.el6

 You could try using --skip-broken to work around the problem

 You could try running: rpm -Va --nofiles --nodigest

It looks like it is all development stuff. To narrow down the issue I decided to pick away at the upgrade so I did:

yum update app-mail*

yum update app-a*

yum update xorg*

yum update app-base*

yum update yum* php*

yum update lin*

yum update lib*

yum update open*

yum update python* perl* samba*

yum update c*

All worked (I think).
I got fed up with this and to get a new error log I did:

yum update

and it all went through. I suspect that somewhere between updating app-base and yum*, the repo list changed so all dependencies got resolved successfully.

This post is just for info.