I get an error message when opening a book. What now?

This issue may be related to the app version. It is important that you always have the latest app version from the Google Playstore (Android) or iTunes Appstore (iOS) installed on your device.

Tip: To find out which app version you currently have installed, simply tap on the burger menu in the top left of the app. The version number is at the bottom left under the logout button. You can always find the latest version of the app in the Google Playstore under "About this app" or in the iTunes Appstore under "News".