Using Stokes' theorem, the line integral of a vector field gives a surface integral of the curl of the vector field, and after that, if we apply Gauss' divergence theorem in that, it gives a volume integral of the divergence of the curl of that vector field. But we know the divergence of the curl of a vector field is $0$. … so how can it be possible? Where is the mistake??
For Stokes, your curved line is closed and bounds a surface. For Gauss, your surface is closed and bounds a volume. Both basically say the same thing, relating a border to the inside. But the out of the first does not fit the in of the second, even if both are "surfaces" ;-)