Received a 301 response. This might indicate a problem.

I am having problems with WP mltisite, so I installed a second instance of vanilla WP.

I have added SS as a plugin, but when generating, I get (on the Diagnostic page) the note

Received a 301 response. This might indicate a problem.

I have chmodded the temp output dir and the final otput dir.

How can I figure out what else I need to do?