In world update, avahi and cups block each other because avahi depends on sys-apps/dbus-0.62-r2, and cups depends on sys-apps/dbus-1.0.2 . I don't see how those two packages could be conflicting packages, perhaps adding an extra slot for dbus to install 2 different versions at once? Reproducible: Always Steps to Reproduce: 1.emerge -Dvut world 2. 3. Actual Results: # emerge -Davut world These are the packages that would be merged, in reverse order: Calculating world dependencies / !!! Multiple versions within a single package slot have been !!! pulled into the dependency graph: ('ebuild', '/', 'sys-apps/dbus-0.62-r2', 'merge') pulled in by ('ebuild', '/', 'net-dns/avahi-0.6.16-r1', 'merge') ('ebuild', '/', 'sys-apps/dbus-1.0.2', 'merge') pulled in by ('ebuild', '/', 'net-print/cups-1.2.7', 'merge') It may be possible to solve this problem by using package.mask to prevent one of those packages from being selected. However, it is also possible that conflicting dependencies exist such that they are impossible to satisfy simultaneously. If such a conflict exists in the dependencies of two different packages, then those packages can not be installed simultaneously. For more information, see MASKED PACKAGES section in the emerge man page or refer to the Gentoo Handbook. !!! Depgraph creation failed.
*** This bug has been marked as a duplicate of bug 157201 ***