[WM17] - Suddenly android app has statred giving error

Hello,

This app was developed in WM 17 and is being used for more than a year now.

But all of a sudden it has started giving this very wired error. "....Specific subscript [51] is invalid.... Only visible elements are available in programming..."
I am attaching the image captured for reference.
[attachment 2231 UnknownError.jpg]

TIA
Yogi Yang