I'm sorry my too late answer.

xos_kernel_xoops2 ...?

2.0.14 looks far different from 2.0.13.x

Though I know I have to make independent environment for 2.0.14, I'm very busy in Juny because of my work and watching Tour de France.

BTW, I guess there is no problem in mainfile.php

I know some modules include common.php after including mainfile.php with 'nocommon'.

List the modules you've installed.