The const keyword is now used to denote constant functions that do not affect the object, and for function arguments to denote that the object passed cannot be changed.
This should not affect your application except for where you are overriding virtual functions which now have a different signature. If functions are not being called which were previously, check whether there is a parameter mismatch (or function type mismatch) involving consts.
Try to use the const keyword in your own code where possible.