On the top line of the Android Samsung 4 phone when you turn it on, there are 4 tiny triangle symbols that look like tepees across the top with the download arrows. What do they mean?
Welcome to Android Central! sfoLAX is correct. It can also happen if you went to Google Play Store, tapped Update All, and then while apps were updating, a Google Play Services update swooped in (it updates on its own), which can derail the other apps that were in the process of updating.