v1.class' does not exist.

[He-Pin]

When compiling Akka

[error] java.lang.IllegalArgumentException: requirement failed: Source file '/Users/kerr/IdeaProjects/akka/akka-docs/target/test-classes/docs/persistence/v1.class' does not exist.
[error] 	at scala.Predef$.require(Predef.scala:277)
[error] 	at sbt.io.IO$.copyFile(IO.scala:823)
[error] 	at sbt.io.IO$.move(IO.scala:1042)
[error] 	at sbt.internal.inc.ClassFileManager$TransactionalClassFileManager.move(ClassFileManager.scala:113)
[error] 	at sbt.internal.inc.ClassFileManager$TransactionalClassFileManager.$anonfun$delete$4(ClassFileManager.scala:88)
[error] 	at scala.collection.IndexedSeqOptimized.foreach(IndexedSeqOptimized.scala:32)
[error] 	at scala.collection.IndexedSeqOptimized.foreach$(IndexedSeqOptimized.scala:29)
[error] 	at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:194)
[error] 	at sbt.internal.inc.ClassFileManager$TransactionalClassFileManager.delete(ClassFileManager.scala:87)
[error] 	at xsbti.compile.WrappedClassFileManager.delete(WrappedClassFileManager.java:43)
[error] 	at sbt.internal.inc.Incremental$.prune(Incremental.scala:128)
[error] 	at sbt.internal.inc.IncrementalCommon.recompileClasses(IncrementalCommon.scala:113)
[error] 	at sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:63)
[error] 	at sbt.internal.inc.Incremental$.$anonfun$compile$3(Incremental.scala:89)
[error] 	at sbt.internal.inc.Incremental$.manageClassfiles(Incremental.scala:134)
[error] 	at sbt.internal.inc.Incremental$.compile(Incremental.scala:80)
[error] 	at sbt.internal.inc.IncrementalCompile$.apply(Compile.scala:67)
[error] 	at sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:311)
[error] 	at sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:269)
[error] 	at sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:159)
[error] 	at sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:238)
[error] 	at sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:69)
[error] 	at sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:1544)
[error] 	at sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:1518)
[error] 	at scala.Function1.$anonfun$compose$1(Function1.scala:44)
[error] 	at sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:40)
[error] 	at sbt.std.Transform$$anon$4.work(System.scala:67)
[error] 	at sbt.Execute.$anonfun$submit$2(Execute.scala:269)
[error] 	at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:16)
[error] 	at sbt.Execute.work(Execute.scala:278)
[error] 	at sbt.Execute.$anonfun$submit$1(Execute.scala:269)
[error] 	at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:178)
[error] 	at sbt.CompletionService$$anon$2.call(CompletionService.scala:37)
[error] 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error] 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[error] 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[error] 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[error] 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[error] 	at java.lang.Thread.run(Thread.java:748)
[error] (akka-docs / Test / compileIncremental) java.lang.IllegalArgumentException: requirement failed: Source file '/Users/kerr/IdeaProjects/akka/akka-docs/target/test-classes/docs/persistence/v1.class' does not exist.
[error] Total time: 45 s, completed 2018-10-29 19:11:31