Luring users back after an incomplete upload

In the mobile world, users are often switching context quickly. Often, once starting a media upload, they will background the app with the upload and switch to say, writing their grandma about how they miss her.

To complete the upload, one option on iOS is background upload for 15 seconds, but if that time runs out, what do we do? Send an annoying notification? Email? How do we signal an error?

Notice the “!” for the failed message. Haven’t seen any apps utilize this well-known convention.