diff --git a/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala b/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
index 082c18419..61e93050b 100644
--- a/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
@@ -42,7 +42,10 @@ private[sbt] abstract class AbstractTaskExecuteProgress extends ExecuteProgress[
   }
 
   override def afterWork[A](task: Task[A], result: Either[Task[A], Result[A]]): Unit = {
-    timings.get(task).stop()
+    timings.get(task) match {
+      case null =>
+      case t    => t.stop()
+    }
     activeTasksMap.remove(task)
 
     // we need this to infer anonymous task names
@@ -51,6 +54,11 @@ private[sbt] abstract class AbstractTaskExecuteProgress extends ExecuteProgress[
     }
   }
 
+  protected def reset(): Unit = {
+    activeTasksMap.clear()
+    timings.clear()
+  }
+
   private[this] val taskNameCache = TrieMap.empty[Task[_], String]
   protected def taskName(t: Task[_]): String =
     taskNameCache.getOrElseUpdate(t, taskName0(t))
diff --git a/main/src/main/scala/sbt/internal/TaskProgress.scala b/main/src/main/scala/sbt/internal/TaskProgress.scala
index ed74d20b1..494520fcc 100644
--- a/main/src/main/scala/sbt/internal/TaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/TaskProgress.scala
@@ -101,6 +101,7 @@ private[sbt] class TaskProgress private ()
   }
 
   override def afterAllCompleted(results: RMap[Task, Result]): Unit = {
+    reset()
     // send an empty progress report to clear out the previous report
     appendProgress(ProgressEvent("Info", Vector(), Some(lastTaskCount.get), None, None))
   }
@@ -132,8 +133,12 @@ private[sbt] class TaskProgress private ()
     StandardMain.exchange.updateProgress(event)
   private[this] def active: Vector[Task[_]] = activeTasks.toVector.filterNot(Def.isDummy)
   private[this] def activeExceedingThreshold: Vector[(Task[_], Long)] = active.flatMap { task =>
-    val elapsed = timings.get(task).currentElapsedMicros
-    if (elapsed.micros > threshold) Some[(Task[_], Long)](task -> elapsed) else None
+    timings.get(task) match {
+      case null => None
+      case t =>
+        val elapsed = t.currentElapsedMicros
+        if (elapsed.micros > threshold) Some[(Task[_], Long)](task -> elapsed) else None
+    }
   }
   private[this] def report(): Unit = {
     val currentTasks = activeExceedingThreshold