Seaside is still developed, but if I were writing a website in Smalltalk right now, I'd be using one of the REST frameworks along with Amber Smalltalk, not Seaside. IMHO, Seaside is an amazing and beautiful piece of technology whose time has passed. I'd personally probably look at something like Iliad instead.
Yes seaside is still in active development and there is progress on getting a nice configuration working on Pharo 2.0. Until then you can use our manual build from https://ci.inria.fr/pharo-contribution/job/Seaside-2.0/ to test it.
Seaside works, yet it has not been officially release for 2.0 hence we rely on a gofer script to load all dependencies.
What error? I doubt it's related to seaside. And for the configuration we mostly need somebody to do it :) since the seaside config is pretty big on its own you got to be careful when changing things for a new release.
Ah, I see. I stop by seaside.st every once and a while, and it doesn't seem to have been updated with any new news for a long time. It would be cool to mention some of these developments on its front page.