Upgrading Spark from Scala 2.11 to Scala 2.12 was a huge effort. See here for more discussion: https://contributors.scala-lang.org/t/spark-as-a-scala-gateway-d

Upgrading Spark from Scala 2.11 to Scala 2.12 was a huge effort. See here for more discussion: https://contributors.scala-lang.org/t/spark-as-a-scala-gateway-drug-and-the-2-12-failure/1747 https://contributors.scala-lang.org/t/spark-as-a-scala-gatew... Some projects are easier to upgrade, but for complex projects, minor Scala version bumps can be quite challenging.