Subdivision Surface modifier above level 1 subdivide causes boolean modifier to break I am trying to cut out ridges on an object using another object. When I apply subdivision on it, level 1 is alright, but level 2 onwards weird stuff is happening. Images below illustrate my issues better.

Boolean cutter, applied with level 1 subdivision work fine.

Another view, with the cutters hidden.

Modifier stack.

Now with level 2 subdivision.

Now with level 3 subdivision. I did not unhide the cutter object, it just appeared.
You basically want to make sure that the vertices, edges and faces of the cutting object never sit directly on top of those of the object cutted into. Try scaling or moving the cutting object by only a few micro- or millimeters. Finding a good position obviously becomes harder with each subdivision, since there are more possibilities of nearly identical vertices appearing.