-Make a portfolio with at least one page and save it (I used "Simple HTML" layout, but it probably doesn't matter)
-Click on the portfolio's name to make it pop up a new page with the portfolio on it
-Close window, then click on the Permissions link in portfolio
-Either click save or cancel (doesn't matter)
-This throws an error
Possible reason: some kind of navigation stack thinks that the last navigated page was the portfolio, and since permissions is a helper, when it tries to go back, it goes back to the portfolio instead.