I am using a JSON extension which relies on Mandubian\'s play-json 2.2-SNAPSHOT. Everything worked fine until now I have a project based on Scala-STM. sbt reports the following
Updated Play2 2.2 - downgrading to SBT from 0.13.0 -> 0.12.4 didn't work with me, but excluding using exclude("org.scala-stm", "scala-stm_2.10.0") on ALL app-specific dependencies I had worked fine -- anyway -- none of my dependencies shouldn't have anything to do with scala-stm.
You can get around this by removing scala-stm with exclude
"dependencyGroupId" %% "dependencyArtifactId" % "dependencyVersion" exclude("org.scala-stm", "scala-stm_2.10.0")
Do not forget to do sbt clean.
If you'd like to see all libraries being pulled in to your SBT project, you can use the SBT dependency graph plugin.
Using this, you can see why scala-stm is being pulled in, and also check for other conflicting scala 2.10 and 2.11 dependencies.