diff --git a/main-command/src/main/scala/sbt/State.scala b/main-command/src/main/scala/sbt/State.scala
index d7db6a51f..00a2d946f 100644
--- a/main-command/src/main/scala/sbt/State.scala
+++ b/main-command/src/main/scala/sbt/State.scala
@@ -72,12 +72,15 @@ final case class State(
  * @param currentExecId provide the execId extracted from the original State.
  * @param combinedParser the parser extracted from the original State.
  */
+@deprecated("unused", "1.4.2")
 private[sbt] final case class SafeState(
     currentExecId: Option[String],
     combinedParser: Parser[() => sbt.State]
 )
 
+@deprecated("unused", "1.4.2")
 private[sbt] object SafeState {
+  @deprecated("use StandardMain.exchange.withState", "1.4.2")
   def apply(s: State) = {
     new SafeState(
       currentExecId = s.currentCommand.map(_.execId).flatten,
diff --git a/main/src/main/scala/sbt/EvaluateTask.scala b/main/src/main/scala/sbt/EvaluateTask.scala
index cc3c4dc26..624c0c2f4 100644
--- a/main/src/main/scala/sbt/EvaluateTask.scala
+++ b/main/src/main/scala/sbt/EvaluateTask.scala
@@ -413,9 +413,13 @@ object EvaluateTask {
       (dummyRoots, roots) :: (Def.dummyStreamsManager, streams) :: (dummyState, state) :: dummies
     )
 
+  @deprecated("use StandardMain.exchange.withState to obtain an instance of State", "1.4.2")
   val lastEvaluatedState: AtomicReference[SafeState] = new AtomicReference()
+  @deprecated("use currentlyRunningTaskEngine", "1.4.2")
   val currentlyRunningEngine: AtomicReference[(SafeState, RunningTaskEngine)] =
     new AtomicReference()
+  private[sbt] val currentlyRunningTaskEngine: AtomicReference[RunningTaskEngine] =
+    new AtomicReference()
 
   /**
    * The main method for the task engine.
@@ -486,7 +490,7 @@ object EvaluateTask {
         shutdownImpl(true)
       }
     }
-    currentlyRunningEngine.set((SafeState(state), runningEngine))
+    currentlyRunningTaskEngine.set(runningEngine)
     // Register with our cancel handler we're about to start.
     val strat = config.cancelStrategy
     val cancelState = strat.onTaskEngineStart(runningEngine)
@@ -494,8 +498,7 @@ object EvaluateTask {
     try run()
     finally {
       strat.onTaskEngineFinish(cancelState)
-      currentlyRunningEngine.set(null)
-      lastEvaluatedState.set(SafeState(state))
+      currentlyRunningTaskEngine.set(null)
     }
   }
 
diff --git a/main/src/main/scala/sbt/internal/server/NetworkChannel.scala b/main/src/main/scala/sbt/internal/server/NetworkChannel.scala
index 77891846a..2e4cec4c0 100644
--- a/main/src/main/scala/sbt/internal/server/NetworkChannel.scala
+++ b/main/src/main/scala/sbt/internal/server/NetworkChannel.scala
@@ -422,58 +422,50 @@ final class NetworkChannel(
   protected def onCompletionRequest(execId: Option[String], cp: CompletionParams) = {
     if (initialized) {
       try {
-        Option(EvaluateTask.lastEvaluatedState.get) match {
-          case Some(sstate) =>
-            import sbt.protocol.codec.JsonProtocol._
-            def completionItems(s: State) = {
-              Parser
-                .completions(s.combinedParser, cp.query, cp.level.getOrElse(9))
-                .get
-                .flatMap { c =>
-                  if (!c.isEmpty) Some(c.append.replaceAll("\n", " "))
-                  else None
-                }
-                .map(c => cp.query + c)
-            }
-            val (items, cachedMainClassNames, cachedTestNames) = StandardMain.exchange.withState {
-              s =>
-                val scopedKeyParser: Parser[Seq[Def.ScopedKey[_]]] =
-                  Act.aggregatedKeyParser(s) <~ Parsers.any.*
-                Parser.parse(cp.query, scopedKeyParser) match {
-                  case Right(keys) =>
-                    val testKeys =
-                      keys.filter(k => k.key.label == "testOnly" || k.key.label == "testQuick")
-                    val (testState, cachedTestNames) = testKeys.foldLeft((s, true)) {
-                      case ((st, allCached), k) =>
-                        SessionVar.loadAndSet(sbt.Keys.definedTestNames in k.scope, st, true) match {
-                          case (nst, d) => (nst, allCached && d.isDefined)
-                        }
+        StandardMain.exchange.withState { sstate =>
+          import sbt.protocol.codec.JsonProtocol._
+          def completionItems(s: State) = {
+            Parser
+              .completions(s.combinedParser, cp.query, cp.level.getOrElse(9))
+              .get
+              .flatMap { c =>
+                if (!c.isEmpty) Some(c.append.replaceAll("\n", " "))
+                else None
+              }
+              .map(c => cp.query + c)
+          }
+          val (items, cachedMainClassNames, cachedTestNames) = {
+            val scopedKeyParser: Parser[Seq[Def.ScopedKey[_]]] =
+              Act.aggregatedKeyParser(sstate) <~ Parsers.any.*
+            Parser.parse(cp.query, scopedKeyParser) match {
+              case Right(keys) =>
+                val testKeys =
+                  keys.filter(k => k.key.label == "testOnly" || k.key.label == "testQuick")
+                val (testState, cachedTestNames) = testKeys.foldLeft((sstate, true)) {
+                  case ((st, allCached), k) =>
+                    SessionVar.loadAndSet(sbt.Keys.definedTestNames in k.scope, st, true) match {
+                      case (nst, d) => (nst, allCached && d.isDefined)
                     }
-                    val runKeys = keys.filter(_.key.label == "runMain")
-                    val (runState, cachedMainClassNames) = runKeys.foldLeft((testState, true)) {
-                      case ((st, allCached), k) =>
-                        SessionVar.loadAndSet(sbt.Keys.discoveredMainClasses in k.scope, st, true) match {
-                          case (nst, d) => (nst, allCached && d.isDefined)
-                        }
-                    }
-                    (completionItems(runState), cachedMainClassNames, cachedTestNames)
-                  case _ => (completionItems(s), true, true)
                 }
+                val runKeys = keys.filter(_.key.label == "runMain")
+                val (runState, cachedMainClassNames) = runKeys.foldLeft((testState, true)) {
+                  case ((st, allCached), k) =>
+                    SessionVar.loadAndSet(sbt.Keys.discoveredMainClasses in k.scope, st, true) match {
+                      case (nst, d) => (nst, allCached && d.isDefined)
+                    }
+                }
+                (completionItems(runState), cachedMainClassNames, cachedTestNames)
+              case _ => (completionItems(sstate), true, true)
             }
-            respondResult(
-              CompletionResponse(
-                items = items.toVector,
-                cachedMainClassNames = cachedMainClassNames,
-                cachedTestNames = cachedTestNames
-              ),
-              execId
-            )
-          case _ =>
-            respondError(
-              ErrorCodes.UnknownError,
-              "No available sbt state",
-              execId
-            )
+          }
+          respondResult(
+            CompletionResponse(
+              items = items.toVector,
+              cachedMainClassNames = cachedMainClassNames,
+              cachedTestNames = cachedTestNames
+            ),
+            execId
+          )
         }
       } catch {
         case NonFatal(_) =>
@@ -498,9 +490,10 @@ final class NetworkChannel(
       )
 
       try {
-        Option(EvaluateTask.currentlyRunningEngine.get) match {
-          case Some((state, runningEngine)) =>
-            val runningExecId = state.currentExecId.getOrElse("")
+        Option(EvaluateTask.currentlyRunningTaskEngine.get) match {
+          case Some(runningEngine) =>
+            val runningExecId =
+              StandardMain.exchange.withState(_.currentCommand.flatMap(_.execId).getOrElse(""))
             val expected = StandardMain.exchange.withState(
               _.get(BasicCommands.execMap)
                 .flatMap(s => s.get(crp.id) orElse s.get("\u2668" + crp.id))
@@ -936,9 +929,10 @@ object NetworkChannel {
       id: String
   ): Either[String, String] = {
 
-    Option(EvaluateTask.currentlyRunningEngine.get) match {
-      case Some((state, runningEngine)) =>
-        val runningExecId = state.currentExecId.getOrElse("")
+    Option(EvaluateTask.currentlyRunningTaskEngine.get) match {
+      case Some(runningEngine) =>
+        val runningExecId =
+          StandardMain.exchange.withState(_.currentCommand.flatMap(_.execId).getOrElse(""))
 
         def checkId(): Boolean = {
           if (runningExecId.startsWith("\u2668")) {