Oh right … I think the was no 1.0 migration guide as the changes were more internal regarding restructuring (for users, the main features were introduced in 0.4 with deprecation warnings and then made final in 1.0).
In either case, since the OP’s code base is coming from 0.3, this 0.4 migration guide is the place to start. And then maybe having a look at some of the changes in 1.0 via the changelog: https://github.com/pytorch/pytorch/releases/tag/v1.0.0 11