Can not enable data roaming I am abroad and when I enable the Mobile data option, i get a warning triangle in the notification area with the text "You have lost data connectivity because you left your home network with data roaming turned off."

Turning Data roaming on does not help. Apps claim I have no internet connection.

What is wrong?

One way to understand the message is that data roaming should have been enabled before leaving the home network. Could that be the reason?

My phone is a Samsung Galaxy S3 (i9300) with Android version 4.3
Turns out the APN settings were wrong. After correcting them, it works.