Boolean difference modifier not working on a custom mesh I'm trying to cut away a curved part inside a custom mesh with the help of a cylinder but the boolean modifier doesn't seems to work, When I try it with another  inbuilt meshes it works I have applied the boolean modifier on the custom mesh and then selected the cylinder for boolean
(Assuming Blender 2.80)
The anvil has a defect geometry. To fix this, select the anvil, go edit mode.
Then "Merge Vertice->By Distance" and leave Edit mode. Then it looks like this:


PS: I switched the cylinder into "Wire" display...