0.39.835 - Project doesn't compile anymore

Upgraded to 0.39.835 from 0.38.437 and my project doesn't compile anymore with the SBT incremental compiler. I get the following error, plus hundreds more. Most of the errors are about not finding packages or classes or not finding the implicit conversion that worked before. The IntelliJ compiler works OK.

Error:scala: Error: scala.collection.immutable.$colon$colon.hd$1()Ljava/lang/Object;
java.lang.NoSuchMethodError: scala.collection.immutable.$colon$colon.hd$1()Ljava/lang/Object;
 at xsbt.api.HashAPI.visit(HashAPI.scala:29)
 at xsbt.api.HashAPI.hashStructure(HashAPI.scala:325)
 at xsbt.api.HashAPI.hashClass0(HashAPI.scala:148)
 at xsbt.api.HashAPI$$anonfun$hashClass$1.apply(HashAPI.scala:142)
 at xsbt.api.HashAPI$$anonfun$hashClass$1.apply(HashAPI.scala:142)
 at xsbt.api.HashAPI.visit(HashAPI.scala:31)
 at xsbt.api.HashAPI.hashClass(HashAPI.scala:142)
 at xsbt.api.HashAPI.hashDefinition(HashAPI.scala:135)
 at xsbt.api.HashAPI$$anonfun$hashDefinitions$1.apply(HashAPI.scala:125)
 at xsbt.api.HashAPI$$anonfun$hashDefinitions$1.apply(HashAPI.scala:125)
 at xsbt.api.HashAPI$$anonfun$2.apply(HashAPI.scala:95)
 at xsbt.api.HashAPI$$anonfun$2.apply(HashAPI.scala:91)
 at scala.collection.immutable.List.map(List.scala:274)
 at xsbt.api.HashAPI.hashSymmetric(HashAPI.scala:91)
 at xsbt.api.HashAPI.hashDefinitions(HashAPI.scala:125)
 at xsbt.api.HashAPI.hashStructure0(HashAPI.scala:331)
 at xsbt.api.HashAPI$$anonfun$hashStructure$1.apply(HashAPI.scala:325)
 at xsbt.api.HashAPI$$anonfun$hashStructure$1.apply(HashAPI.scala:325)
 at xsbt.api.HashAPI.visit(HashAPI.scala:31)
 at xsbt.api.HashAPI.hashStructure(HashAPI.scala:325)
 at xsbt.api.HashAPI.hashClass0(HashAPI.scala:148)
 at xsbt.api.HashAPI$$anonfun$hashClass$1.apply(HashAPI.scala:142)
 at xsbt.api.HashAPI$$anonfun$hashClass$1.apply(HashAPI.scala:142)
 at xsbt.api.HashAPI.visit(HashAPI.scala:31)
 at xsbt.api.HashAPI.hashClass(HashAPI.scala:142)
 at xsbt.api.HashAPI.hashDefinition(HashAPI.scala:135)
 at xsbt.api.HashAPI$$anonfun$hashDefinitions$1.apply(HashAPI.scala:125)
 at xsbt.api.HashAPI$$anonfun$hashDefinitions$1.apply(HashAPI.scala:125)
 at xsbt.api.HashAPI$$anonfun$2.apply(HashAPI.scala:95)
 at xsbt.api.HashAPI$$anonfun$2.apply(HashAPI.scala:91)
 at scala.collection.immutable.List.map(List.scala:278)
 at xsbt.api.HashAPI.hashSymmetric(HashAPI.scala:91)
 at xsbt.api.HashAPI.hashDefinitions(HashAPI.scala:125)
 at xsbt.api.HashAPI.hashAPI(HashAPI.scala:116)
 at xsbt.api.HashAPI$.apply(HashAPI.scala:15)
 at sbt.inc.AnalysisCallback.api(Compile.scala:152)
 at sbt.compiler.AnalysisCallbackAdapter.api(AnalysisCallbackAdapter.scala:17)
 at xsbt.API$ApiPhase.processScalaUnit(API.scala:49)
 at xsbt.API$ApiPhase.processUnit(API.scala:38)
 at xsbt.API$ApiPhase$$anonfun$run$1.apply(API.scala:34)
 at xsbt.API$ApiPhase$$anonfun$run$1.apply(API.scala:34)
 at scala.collection.Iterator$class.foreach(Iterator.scala:743)
 at scala.collection.AbstractIterator.foreach(Iterator.scala:1174)
 at xsbt.API$ApiPhase.run(API.scala:34)
 at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1625)
 at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1610)
 at scala.tools.nsc.Global$Run.compileSources(Global.scala:1605)
 at scala.tools.nsc.Global$Run.compile(Global.scala:1703)
 at xsbt.CachedCompiler0.run(CompilerInterface.scala:126)
 at xsbt.CachedCompiler0.run(CompilerInterface.scala:102)
 at xsbt.CompilerInterface.run(CompilerInterface.scala:27)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:483)
 at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:102)
 at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:48)
 at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:41)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1$$anonfun$apply$3$$anonfun$apply$1.apply$mcV$sp(AggressiveCompile.scala:106)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1$$anonfun$apply$3$$anonfun$apply$1.apply(AggressiveCompile.scala:106)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1$$anonfun$apply$3$$anonfun$apply$1.apply(AggressiveCompile.scala:106)
 at sbt.compiler.AggressiveCompile.sbt$compiler$AggressiveCompile$$timed(AggressiveCompile.scala:173)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1$$anonfun$apply$3.apply(AggressiveCompile.scala:105)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1$$anonfun$apply$3.apply(AggressiveCompile.scala:102)
 at scala.Option.foreach(Option.scala:245)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1.apply(AggressiveCompile.scala:102)
 at sbt.compiler.AggressiveCompile$$anonfun$6$$anonfun$compileScala$1$1.apply(AggressiveCompile.scala:102)
 at scala.Option.foreach(Option.scala:245)
 at sbt.compiler.AggressiveCompile$$anonfun$6.compileScala$1(AggressiveCompile.scala:102)
 at sbt.compiler.AggressiveCompile$$anonfun$6.apply(AggressiveCompile.scala:151)
 at sbt.compiler.AggressiveCompile$$anonfun$6.apply(AggressiveCompile.scala:89)
 at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:39)
 at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:37)
 at sbt.inc.Incremental$.cycle(Incremental.scala:75)
 at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:34)
 at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:33)
 at sbt.inc.Incremental$.manageClassfiles(Incremental.scala:42)
 at sbt.inc.Incremental$.compile(Incremental.scala:33)
 at sbt.inc.IncrementalCompile$.apply(Compile.scala:27)
 at sbt.compiler.AggressiveCompile.compile2(AggressiveCompile.scala:164)
 at sbt.compiler.AggressiveCompile.compile1(AggressiveCompile.scala:73)
 at org.jetbrains.jps.incremental.scala.local.SbtCompiler.compile(SbtCompiler.scala:59)
 at org.jetbrains.jps.incremental.scala.local.LocalServer.compile(LocalServer.scala:25)
 at org.jetbrains.jps.incremental.scala.remote.Main$.make(Main.scala:64)
 at org.jetbrains.jps.incremental.scala.remote.Main$.nailMain(Main.scala:22)
 at org.jetbrains.jps.incremental.scala.remote.Main.nailMain(Main.scala)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:483)
 at com.martiansoftware.nailgun.NGSession.run(NGSession.java:319)