why do I see orange triangle with exclamation mark in the top left corner of the screen

[svetushka]

Hi everybody!
I am using s4 mini and it shows orange triangle with exclamation mark in the top left corner of the screen, I understand it is some sort of error warning but can't localise it, I know it is not related to WI-FI, data or battery issues. How do I find out what is wrong, or how I troubleshoot this. Any ideas will be appreciated.

 

[Wm7Long]

When ever I get a notification in upper left of top bar, swiping down from there pulls down my notification 'shade' with quick settings and expanded information regarding the new notification icon. Long pressing on the expanded notification then brings up something useful.