SBT project refresh failed [IntelliJ, Scala, SBT]

Question

Whenever I try to enable auto-import in IntelliJ it always gives me this error:

SBT 'Example' project refresh failed

Error while importing SBT project:
...
[warn] ==== public: tried
[warn]   https://repo1.maven.org/maven2/org/scalatest/scalatest_2.12/2.2.6/scalatest_2.12-2.2.6.pom
[info] Resolving org.scala-lang#scala-compiler;2.12.0 ...
[info] Resolving org.scala-lang#scala-reflect;2.12.0 ...
[info] Resolving org.scala-lang.modules#scala-xml_2.12;1.0.5 ...
[info] Resolving jline#jline;2.14.1 ...
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  ::          UNRESOLVED DEPENDENCIES         ::
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  :: org.scalatest#scalatest_2.12;2.2.6: not found
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn] 
[warn]  Note: Unresolved dependencies path:
[warn]      org.scalatest:scalatest_2.12:2.2.6 (/Users/sarahbaka/Desktop/Scala/Example/build.sbt#L7-8)
[warn]        +- default:example_2.12:1.0
[trace] Stack trace suppressed: run 'last *:update' for the full output.
[trace] Stack trace suppressed: run 'last *:ssExtractDependencies' for the full output.
[error] (*:update) sbt.ResolveException: unresolved dependency: org.scalatest#scalatest_2.12;2.2.6: not found
[error] (*:ssExtractDependencies) sbt.ResolveException: unresolved dependency: org.scalatest#scalatest_2.12;2.2.6: not found
[error] Total time: 4 s, completed 08-Nov-2016 22:24:34</pre><br/>

I already installed the JetBrains Scala plugin, then opened a directory with an SBT build and reset/restarted my cache (File -> Invalidate Caches / Restart). But it still doesn't work! Does anyone know why?

Answer 1

Your scalatest dependency is misconfigured. You want scalatest version 2.6 published for Scala 2.12. There is no such combination, hence your build fails. If you have a look at which version of scalatest is available for Scala 2.12, here's the link. As you can see, it's only version 3.0.0. So, you have 3 options (those are changes in your build.sbt file you need to make):

1. Update your scalatest version to 3.0.0: libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.0" % Test
2. Downgrade your Scala version to 2.11: scalaVersion := "2.11.8"
3. Both of the above

I'd say it's a bit too early to use Scala 2.12, since it was only released a couple of days ago, and not all of the dependencies are published for it yet. Scala major versions (2.11 vs 2.12 is a major version upgrade for Scala) are not binary compatible, so you can't use a library compiled with one Scala version in a project that uses the other.

At the same time, I'd go with scalatest 3.0.0 version, since it's the stable one. So all in all, I'd go for option 3 at the moment, even though options 1 and 2 will fix this particular problem, in different ways.