You may be unable to send a picture or video message, or you may receive error messages if your phone is connected to the wrong network or if data is disabled on your phone. But don’t worry! It’s easy to fix. Here’s what you can do:
Go to Settings › Wireless & Networks › Mobile Networks or Data
Once there, make sure data is enabled.
Go to Settings > System Update > Update Profile or PRL
Select “Update Profile” or “Update PRL” (if you see both, please update both).
Once selected, just wait a moment while the phone finishes updating. Some phones may restart at this point.