Debug not working with play framework activator, scala and eclipse

Question

There are many posts on this, the instructions are straight forward, but for the life of me I can't get the debugger to stop at breakpoints.

My environment is

• eclipse 4.4.1
• scala 2.11
• scala IDE 4.1.0.nightly
• play framework 2.3.3
• play support in Scala IDE 0.4.6

I launch activator as follows

activator -jvm-debug 9999 run

I have set up a remote java application debug configuration with standard socket attach. The debug configuration runs, attaches to the remote and launches a bunch of sbt threads.

But, it will not stop in the debugger! It doesn't seem that hard, what am I doing wrong?

Edit: I have this problem in a project I've been working on for a while and in a brand new, untouched instantiation of the play-anguale-require-seed project. Here is the build.sbt for that project:

import WebKeys._

// TODO Replace with your project's/module's name
name := """play-angular-require-seed"""

// TODO Set your organization here; ThisBuild means it will apply to all sub-    modules
organization in ThisBuild := "your.organization"

// TODO Set your version here
version := "2.3.7-SNAPSHOT"

// Scala Version, Play supports both 2.10 and 2.11
//scalaVersion := "2.10.4"
scalaVersion := "2.11.4"

lazy val root = (project in file(".")).enablePlugins(PlayScala)

// Dependencies
libraryDependencies ++= Seq(
  filters,
  cache,
  // WebJars (i.e. client-side) dependencies
  "org.webjars" % "requirejs" % "2.1.14-1",
  "org.webjars" % "underscorejs" % "1.6.0-3",
  "org.webjars" % "jquery" % "1.11.1",
  "org.webjars" % "bootstrap" % "3.1.1-2" exclude("org.webjars", "jquery"),
  "org.webjars" % "angularjs" % "1.2.18" exclude("org.webjars", "jquery")
)

// Scala Compiler Options
scalacOptions in ThisBuild ++= Seq(
  "-target:jvm-1.7",
  "-encoding", "UTF-8",
  "-deprecation", // warning and location for usages of deprecated APIs
  "-feature", // warning and location for usages of features that should be                 imported explicitly
  "-unchecked", // additional warnings where generated code depends on assumptions
  "-Xlint", // recommended additional warnings
  "-Ywarn-adapted-args", // Warn if an argument list is modified to match the receiver
  "-Ywarn-value-discard", // Warn when non-Unit expression results are unused
  "-Ywarn-inaccessible",
  "-Ywarn-dead-code"
)

//
// sbt-web configuration
// https://github.com/sbt/sbt-web
//

// Configure the steps of the asset pipeline (used in stage and dist tasks)
// rjs = RequireJS, uglifies, shrinks to one file, replaces WebJars with CDN
// digest = Adds hash to filename
// gzip = Zips all assets, Asset controller serves them automatically when client accepts them
pipelineStages := Seq(rjs, digest, gzip)

// RequireJS with sbt-rjs (https://github.com/sbt/sbt-rjs#sbt-rjs)
// ~~~
RjsKeys.paths += ("jsRoutes" -> ("/jsroutes" -> "empty:"))

//RjsKeys.mainModule := "main"

// Asset hashing with sbt-digest (https://github.com/sbt/sbt-digest)
// ~~~
// md5 | sha1
//DigestKeys.algorithms := "md5"
//includeFilter in digest := "..."
//excludeFilter in digest := "..."

// HTTP compression with sbt-gzip (https://github.com/sbt/sbt-gzip)
// ~~~
// includeFilter in GzipKeys.compress := "*.html" || "*.css" || "*.js"
// excludeFilter in GzipKeys.compress := "..."

// JavaScript linting with sbt-jshint (https://github.com/sbt/sbt-jshint)
// ~~~
// JshintKeys.config := ".jshintrc"

// All work and no play...
emojiLogs


fork in run := true

Answer 1

Kris' comment has the answer! Remove fork in run from the build.sbt or set it to false. I'm not sure if there will downstream consequences.