I have had multiple times when people have to move from their older version of a library that can be 2-4 versions behind to the latest. Most recently an older version of Apache Kafka and confluent schema registry to a new version. They want to move schema registry up to the latest version first but want to make sure there are no breaking changes that would make the old kafka version incompatible when it first turns on (then they will slowly upgrade from slightly new to slightly newer version of kafka to make sure nothing breaks).

I have usually just looked through the release notes to see any listed breaking changes, but is there a better way? Between these specifically, but for really any open source projects that interact?