I tried to use orbeon default login page to login (i.e. http://localhost:8080/orbeon/fr/auth?source=/fr/). After login successfully, it showed the tomcat error page "HTTP Status 403". After that, I manually input the URL http://localhost:8080/orbeon/fr/ and found the account has been already login. Why didn't the page redirect to /fr/ after login? Is some setting missing?
I suspect you're getting this error when the user logs in successfully and that user doesn't have access to that page. If you think the user should have access the page, I'd check that the user has a role that you require in the web.xml
(out-of-the-box, that would be the orbeon-user
role).