Usually via the graph mode we can clearly see what and how the subroutine did,however lucky is not all the time with us,u may get an error message like above.

This error is mostly caused by fallow reasons:

1. there are to much nods that ida can’t change to graph mod,now here is no solution to fix this error

2.the current cursor pos is at a position that ida can’t recognize them as functions

3. a sp-anylized failure happened .