In one of my Gentoo installations I run into this problem when trying to update it, I run these commands

sudo emerge --sync

and then

sudo emerge --update --deep --pretend world

And I got this message

Calculating world dependencies /
!!! All ebuilds that could satisfy ">=sys-libs/e2fsprogs-libs-1.41" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-libs/e2fsprogs-libs-1.41.3-r1 (masked by: required EAPI 2, supported EAPI 1)
- sys-libs/e2fsprogs-libs-1.41.4 (masked by: required EAPI 2, supported EAPI 1)

To solve that problem just run this:

sudo emerge portage

and try again, it should work this time.