Samsung Galaxy core prime error: network error occured.

[AC Question]

All three people in my Mom house use Samsung Galaxy Core Prime. All phones just had the same problem, showed the same message:
Error: Network error occurred.
All phones still can access to internet, but they are not functioning normally like before, when sending pictures, they keep sending pictures more times than expected.

 

[B. Diddy]

Welcome to Android Central! Have they asked their carrier about this?

 

[DreciL]

Mobile network state disabled