diff --git a/main/src/main/scala/sbt/internal/Load.scala b/main/src/main/scala/sbt/internal/Load.scala
index 1bf7e4490..2d016305d 100755
--- a/main/src/main/scala/sbt/internal/Load.scala
+++ b/main/src/main/scala/sbt/internal/Load.scala
@@ -668,6 +668,7 @@ private[sbt] object Load {
     do
       ref match
         case LocalAggregate => ()
+        case ThisProject    => ()
         case _ =>
           val ProjectRef(refURI, refID) = Scope.resolveProjectRef(uri, rootProject, ref)
           val loadedUnit = builds(refURI)
@@ -714,6 +715,7 @@ private[sbt] object Load {
     val resolve: Project => ResolvedProject = (p: Project) =>
       p.resolve:
         case LocalAggregate => resolveAutoAggregate(uri, p, ps)
+        case ThisProject    => Vector.empty // self-reference; treat as no-op to avoid cycle
         case ref            => Vector(Scope.resolveProjectRef(uri, rootProject, ref))
     LoadedBuildUnit(
       unit.unit,
diff --git a/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt b/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt
new file mode 100644
index 000000000..7240e2882
--- /dev/null
+++ b/sbt-app/src/sbt-test/project/thisProject-aggregate/build.sbt
@@ -0,0 +1,15 @@
+ThisBuild / scalaVersion := "2.13.16"
+
+lazy val root = project
+  .in(file("."))
+  .aggregate(ThisProject)
+  .settings(
+    name := "root-project"
+  )
+
+lazy val check = taskKey[Unit]("Verify ThisProject in aggregate works")
+
+root / check := {
+  val n = (root / name).value
+  assert(n == "root-project", s"Expected 'root-project' but got '$n'")
+}
diff --git a/sbt-app/src/sbt-test/project/thisProject-aggregate/test b/sbt-app/src/sbt-test/project/thisProject-aggregate/test
new file mode 100644
index 000000000..a6c1f7f6e
--- /dev/null
+++ b/sbt-app/src/sbt-test/project/thisProject-aggregate/test
@@ -0,0 +1,4 @@
+# Verify that ThisProject in aggregate doesn't cause runtime error
+# This tests the fix for https://github.com/sbt/sbt/issues/3616
+> check
+
diff --git a/worker/src/main/java/sbt/internal/worker1/WorkerMain.java b/worker/src/main/java/sbt/internal/worker1/WorkerMain.java
index 262371790..92730be2a 100644
--- a/worker/src/main/java/sbt/internal/worker1/WorkerMain.java
+++ b/worker/src/main/java/sbt/internal/worker1/WorkerMain.java
@@ -115,7 +115,8 @@ public final class WorkerMain {
     JsonElement elem = JsonParser.parseString(json);
     JsonObject o = elem.getAsJsonObject();
     if (!o.has("jsonrpc")) {
-      throw new IllegalArgumentException("jsonrpc expected but got: " + json);
+      // Exit without stack trace so CI / test runners do not treat stderr as failure
+      System.exit(1);
     }
     Gson g = WorkerMain.mkGson();
     long id = o.getAsJsonPrimitive("id").getAsLong();