Hey @liuiou, thanks for reporting that, it seems there may be an issue with the restoration of the last document you had open. Can you please try tapping and holding the app icon, so you get the shortcut actions, and the select "My Library"? It should open the app without crashing. If this happens again for the same document, please mail it to support@zotero.org, mentioning this thread. If it happens with other documents as well, do let us know.