title: java.lang.NoClassDefFoundError: scala/reflect/internal/Trees
body: <p>I recently encountered a problem where the maven repo cannot be accessed. This was resolved through:</p>
  
  <p><a href="https://issues.sonatype.org/browse/MVNCENTRAL-485" rel="nofollow">https://issues.sonatype.org/browse/MVNCENTRAL-485</a></p>
  
  <p>Howver, after I deleted the ~/.ivy/cache, The following java error pops up:</p>
  
  <pre><code>java.lang.NoClassDefFoundError: scala/reflect/internal/Trees
      at java.lang.ClassLoader.defineClass1(Native Method)
      at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
      at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
      at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
      at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
      at java.lang.ClassLoader.defineClass1(Native Method)   
      at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
      at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
      at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
      at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:270)
      at xsbt.boot.Pre$.xsbt$boot$Pre$$classMissing$1(Pre.scala:68)
      at xsbt.boot.Pre$$anonfun$getMissing$1.apply(Pre.scala:69)
      at   scala.collection.TraversableLike$$anonfun$filter$1.apply(TraversableLike.scala:264)
      at scala.collection.immutable.List.foreach(List.scala:318)
      at org.apache.ivy.core.RelativeUrlResolver.filter(RelativeUrlResolver.java:263)
      at scala.collection.AbstractTraversable.filter(Traversable.scala:105)
      at xsbt.boot.Pre$.getMissing$d83f809$3a8a6f87(Pre.scala:69)
      at xsbt.boot.Launch.checkLoader$2accd70c(Launch.scala:131)
      at xsbt.boot.Launch.xsbt$boot$Launch$$provider$1(Launch.scala:189)
      at xsbt.boot.Launch$$anonfun$xsbt$boot$Launch$$getScalaProvider0$2.apply(Launch.scala:192)
      at xsbt.boot.Launch$$anonfun$xsbt$boot$Launch$$getScalaProvider0$2.apply(Launch.scala:191)
      at scala.Option.flatMap(Option.scala:170)
      at xsbt.boot.Launch.xsbt$boot$Launch$$getScalaProvider0(Launch.scala:191)
      at xsbt.boot.Launch$$anon$3.call(Launch.scala:180)
      at xsbt.boot.Locks$GlobalLock.withLock(Locks.scala:48)
      at xsbt.boot.Locks$.apply0(Locks.scala:31)
      at xsbt.boot.Locks$.apply(Locks.scala:28)
      at xsbt.boot.Launch.locked(Launch.scala:178)
      at xsbt.boot.Launch.getScalaProvider(Launch.scala:180)
      at xsbt.boot.Launch$$anonfun$1.apply(Launch.scala:87)
      at xsbt.boot.Cache.newEntry(Cache.scala:17)
      at xsbt.boot.Cache.apply(Cache.scala:12)
      at xsbt.boot.Launch.getScala(Launch.scala:90)
      at xsbt.boot.Launch.getScala(Launch.scala:89)
      at xsbt.boot.Launch.xsbt$boot$Launch$$getAppProvider0(Launch.scala:160)
      at xsbt.boot.Launch$$anon$2.call(Launch.scala:142)
      at xsbt.boot.Locks$GlobalLock.withChannel$1(Locks.scala:98)
      at xsbt.boot.Locks$GlobalLock.xsbt$boot$Locks$GlobalLock$$withChannelRetries$1(Locks.scala:81)
      at xsbt.boot.Locks$GlobalLock$$anonfun$withFileLock$1.apply(Locks.scala:102)
      at xsbt.boot.Using$.withResource(Using.scala:11)
      at xsbt.boot.Using$.apply(Using.scala:10)
      at xsbt.boot.Locks$GlobalLock.ignoringDeadlockAvoided(Locks.scala:62)
      at xsbt.boot.Locks$GlobalLock.withLock(Locks.scala:52)
      at xsbt.boot.Locks$.apply0(Locks.scala:31)
      at xsbt.boot.Locks$.apply(Locks.scala:28)
      at xsbt.boot.Launch.locked(Launch.scala:178)
      at xsbt.boot.Launch.app(Launch.scala:93)
      at xsbt.boot.Launch.app(Launch.scala:91)
      at xsbt.boot.Launch$.run(Launch.scala:51)
      at xsbt.boot.Launch$$anonfun$explicit$1.apply(Launch.scala:45)
      at xsbt.boot.Launch$.launch(Launch.scala:65)
      at xsbt.boot.Launch$.apply(Launch.scala:16)
      at xsbt.boot.Boot$.runImpl(Boot.scala:32)
      at xsbt.boot.Boot$.main(Boot.scala:21)
      at xsbt.boot.Boot.main(Boot.scala)
  Caused by: java.lang.ClassNotFoundException: scala.reflect.internal.Trees
      at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
      at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
      ... 69 more
  </code></pre>
  
  <p>I am rather new with scala. Does anyone have any idea about this?</p>