Upgrading from 0.18

Automated upgrading with scalafix

Http4s 0.20 comes with a scalafix that does some of the migration automatically.

Before you upgrade manually, we recommend you run this scalafix.

Make sure your scala version is >= 2.11.12 or 2.12.7

Add the scalafix plugin to your project/plugins.sbt or to your global plugins.

addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.9.0")


$ sbt ";scalafixEnable; scalafix github:http4s/http4s/v0_20"

The compiler errors should help you in showing what’s left to upgrade.

For further information about the changes from 0.18, check the changelog