I recently up-graded to 3.6, now when I click on the Series TOC, I get a 404 error. Same thing if I click on any series name from inside an article.
I can still go to next article, or previous article within a series, and the different series are still all together.
eg. Here's one series
And this is the Series TOC:
But as you can see from this article, the series still works:
Do I need to do something to my URLs to make them work again?