I get the Error
Unable to start activity ComponentInfo{de.androidbuch.activiti/de.androidbuch.activiti.task.Activity}: android.view.InflateException: Binar
If you have separate layout files for portrait and landscape modes and are getting an inflation error whenever you change orientation after clicking an item, there is most likely a discrepancy between your layout files.
When you get the error, is it only when you click the item in landscape mode or only in portrait mode or both? Does your TaskDetailsFragment activity use a layout file that could have discrepancies between landscape and portrait modes?