pkg: Cannot solve problem using SAT solver

[Thierry Thomas]

Hello,

Trying to upgrade a machine with `pkg upgrade', it displays these
messages:

pkg: Cannot solve problem using SAT solver:
cannot install package ecs~science/ecs, remove it from request [Y/n]: Y
pkg: Cannot solve problem using SAT solver:
cannot install package apache22~www/apache22, remove it from request [Y/n]: Y
cannot install package mod_php5~www/mod_php5, remove it from request [Y/n]: Y

This is pkg 1.3.6.

Is it possible to upgrade these packages with pkg, or do we need to use
the ports?

Regards,
-- 
Th. Thomas.