diff --git a/nvflare/app_common/abstract/launcher.py b/nvflare/app_common/abstract/launcher.py
index 0cb6024ada..2b3fd3c01d 100644
--- a/nvflare/app_common/abstract/launcher.py
+++ b/nvflare/app_common/abstract/launcher.py
@@ -36,14 +36,11 @@ def finalize(self, fl_ctx: FLContext) -> None:
         pass
 
     @staticmethod
-    def get_app_dir(fl_ctx: FLContext) -> Optional[str]:
+    def get_app_dir(fl_ctx: FLContext) -> str:
         """Gets the deployed application directory."""
-        if fl_ctx is not None:
-            workspace: Workspace = fl_ctx.get_engine().get_workspace()
-            app_dir = workspace.get_app_dir(fl_ctx.get_job_id())
-            if app_dir is not None:
-                return os.path.abspath(app_dir)
-        return None
+        workspace: Workspace = fl_ctx.get_engine().get_workspace()
+        app_dir = workspace.get_app_dir(fl_ctx.get_job_id())
+        return os.path.abspath(app_dir)
 
     @abstractmethod
     def launch_task(self, task_name: str, shareable: Shareable, fl_ctx: FLContext, abort_signal: Signal) -> bool:
diff --git a/tests/unit_test/app_common/launchers/subprocess_launcher_test.py b/tests/unit_test/app_common/launchers/subprocess_launcher_test.py
index 1b0ea2c8e8..fd0e705878 100644
--- a/tests/unit_test/app_common/launchers/subprocess_launcher_test.py
+++ b/tests/unit_test/app_common/launchers/subprocess_launcher_test.py
@@ -12,6 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import shutil
+import tempfile
+
 from nvflare.apis.dxo import DXO, DataKind
 from nvflare.apis.fl_context import FLContext
 from nvflare.apis.signal import Signal
@@ -20,22 +23,30 @@
 
 class TestSubprocessLauncher:
     def test_launch(self):
-        task_name = "__test_task"
-        launcher = SubprocessLauncher("echo 'test'")
-        dxo = DXO(DataKind.WEIGHTS, {})
+        tempdir = tempfile.mkdtemp()
         fl_ctx = FLContext()
+        launcher = SubprocessLauncher("echo 'test'")
+        launcher._app_dir = tempdir
+
         signal = Signal()
+        task_name = "__test_task"
+        dxo = DXO(DataKind.WEIGHTS, {})
         status = launcher.launch_task(task_name, dxo.to_shareable(), fl_ctx, signal)
         assert status is True
+        shutil.rmtree(tempdir)
 
     def test_stop(self):
-        task_name = "__test_task"
-        launcher = SubprocessLauncher("python -c \"for i in range(1000000): print('cool')\"")
-        dxo = DXO(DataKind.WEIGHTS, {})
+        tempdir = tempfile.mkdtemp()
         fl_ctx = FLContext()
+        launcher = SubprocessLauncher("python -c \"for i in range(1000000): print('cool')\"")
+        launcher._app_dir = tempdir
+
         signal = Signal()
+        task_name = "__test_task"
+        dxo = DXO(DataKind.WEIGHTS, {})
         status = launcher.launch_task(task_name, dxo.to_shareable(), fl_ctx, signal)
         assert status is True
         launcher.stop_task(task_name, fl_ctx)
 
         assert launcher._process is None
+        shutil.rmtree(tempdir)