The page requires session state that is no longer available

When browsing OutSystems applications with mobile devices sometimes you receive an error stating: "The page requires session state that is no longer available".

This is the HistoryMissing exception in service studio. It only occurs when you follow a link (with method submit) or a button using your mobile browser (wap1.x/wml or wap2.0/xhtml).

This error occurs in two situations:
- the end user pressed a link or a button from a screen send more than 20 minutes ago.
- the end user pressed the back button too many times.

The correct behavior for your application is to simply redirect the end user to the home page or to a page that makes sense in the current flow. The developer can do it using an exception handler at the screen level flow that redirects "HistoryMissing" exceptions to the home page.

Nevertheless you can further reduce the impact to the end user by avoiding links with method submit. If the developer only uses links with method "link" the end user navigation never raises any "HistoryMissing" exceptions because all the navigation information required by the platform is present in the URL itself.