Web applications can rely on browsers to deal with things such as poor connection, non-existent pages, or server errors. These might not be the best system messages, but they work and are better than nothing.

Apps aren't browsers. This means that native apps have to address errors themselves and communicate problems clearly, so users don't need to wonder whether something has happened with the app, device, or connection.

Designers should work with UX writers and developers to find ways to predict problems and generate meaningful and helpful warnings and error messages for situations like offline states, service failures, or poor Internet connections.

Besides, it's good to consider first- and second-time user experience, the app behavior in the background, ways to minimize user input, and prioritize content, so users don't feel overwhelmed.