sbt assembly error - deduplicate: different file contents found in the following

Question

I get the following error when I do a ./sbt assembly on my Scala project. I saw the first after adding these dependencies to my build.sbt I can compile and run my code.

libraryDependencies  ++= Seq(
  "org.scalanlp" % "breeze_2.10" % "0.7",
  "org.scalanlp" % "breeze-natives_2.10" % "0.7"
)


java.lang.RuntimeException: deduplicate: different file contents found in the following:
/Users/ssimanta/.ivy2/cache/org.spire-math/spire_2.10/jars/spire_2.10-0.7.1.jar:scala/reflect/api/Liftable$$anon$1.class
/Users/ssimanta/.ivy2/cache/org.spire-math/spire-macros_2.10/jars/spire-macros_2.10-0.7.1.jar:scala/reflect/api/Liftable$$anon$1.class
    at sbtassembly.Plugin$Assembly$.sbtassembly$Plugin$Assembly$$applyStrategy$1(Plugin.scala:253)
    at sbtassembly.Plugin$Assembly$$anonfun$15.apply(Plugin.scala:270)
    at sbtassembly.Plugin$Assembly$$anonfun$15.apply(Plugin.scala:267)
    at scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:251)
    at scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:251)
    at scala.collection.Iterator$class.foreach(Iterator.scala:727)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
    at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
    at scala.collection.TraversableLike$class.flatMap(TraversableLike.scala:251)
    at scala.collection.AbstractTraversable.flatMap(Traversable.scala:105)
    at sbtassembly.Plugin$Assembly$.applyStrategies(Plugin.scala:272)
    at sbtassembly.Plugin$Assembly$.x$4$lzycompute$1(Plugin.scala:172)
    at sbtassembly.Plugin$Assembly$.x$4$1(Plugin.scala:170)
    at sbtassembly.Plugin$Assembly$.stratMapping$lzycompute$1(Plugin.scala:170)
    at sbtassembly.Plugin$Assembly$.stratMapping$1(Plugin.scala:170)
    at sbtassembly.Plugin$Assembly$.inputs$lzycompute$1(Plugin.scala:214)
    at sbtassembly.Plugin$Assembly$.inputs$1(Plugin.scala:204)
    at sbtassembly.Plugin$Assembly$.apply(Plugin.scala:230)
    at sbtassembly.Plugin$Assembly$$anonfun$assemblyTask$1.apply(Plugin.scala:373)
    at sbtassembly.Plugin$Assembly$$anonfun$assemblyTask$1.apply(Plugin.scala:370)
    at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
    at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:42)
    at sbt.std.Transform$$anon$4.work(System.scala:64)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:237)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:237)
    at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:18)
    at sbt.Execute.work(Execute.scala:244)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:237)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:237)
    at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:160)
    at sbt.CompletionService$$anon$2.call(CompletionService.scala:30)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
[error] (*:assembly) deduplicate: different file contents found in the following:
[error] /Users/ssimanta/.ivy2/cache/org.spire-math/spire_2.10/jars/spire_2.10-0.7.1.jar:scala/reflect/api/Liftable$$anon$1.class
[error] /Users/ssimanta/.ivy2/cache/org.spire-math/spire-macros_2.10/jars/spire-macros_2.10-0.7.1.jar:scala/reflect/api/Liftable$$anon$1.class
[error] Total time: 2 s, completed Apr 24, 2014 5:39:55 PM

Answer 1

while referring to this Doc I added below snippet in my project which makes work for me

assemblyMergeStrategy in assembly := {   
  case PathList("META-INF", xs @ _*) => MergeStrategy.discard   
  case x => MergeStrategy.first 
}

in build.sbt file