I\'ve created an app using AngularJS with GAE (Google App Engine – Java).
I want to convert it compatible with SEO.
I'm sure you've already solved this, but for anybody else running into this issue:
Basically AngularJS's $locationProvider.html5mode(true) makes use of HTML5's history.pushState(), which artificially changes the user's history and address bar URL without reloading the page. If you create a route (in Angular) for /about, but don't have any matching route on the server, you will run into the issue where reloading the page reveals the fact that it's not there on the server. The simplest solution is to mirror your entry point for your app (/index.html?) for all routes accessible by your app.
See: https://stackoverflow.com/a/16570533/1500501