...If the user somehow manages to open multiple file pickers (e.g. due the app being unresponsive), then only the picked result from the last opened picker will be considered and the promises from previous opened pickers will be rejected with an error that you can check using DocumentPicker.isInProgress(). If mode is set to open, iOS is giving you secure access to a file located outside from your sandbox. In that case Apple is asking you to release the access as soon as you finish using the resource.