diff --git a/UnitySDK/Assets/ML-Agents/Scripts/Academy.cs b/UnitySDK/Assets/ML-Agents/Scripts/Academy.cs
index 7b9b32f132..dc7db49223 100755
--- a/UnitySDK/Assets/ML-Agents/Scripts/Academy.cs
+++ b/UnitySDK/Assets/ML-Agents/Scripts/Academy.cs
@@ -92,7 +92,7 @@ public EnvironmentConfiguration(
              "docs/Learning-Environment-Design-Academy.md")]
     public abstract class Academy : MonoBehaviour
     {
-        private const string kApiVersion = "API-4";
+        private const string kApiVersion = "API-5";
 
         // Fields provided in the Inspector
 
diff --git a/ml-agents/mlagents/envs/environment.py b/ml-agents/mlagents/envs/environment.py
index d729a3d652..51eab97b8d 100644
--- a/ml-agents/mlagents/envs/environment.py
+++ b/ml-agents/mlagents/envs/environment.py
@@ -43,7 +43,7 @@ def __init__(self, file_name=None, worker_id=0,
         atexit.register(self._close)
         self.port = base_port + worker_id
         self._buffer_size = 12000
-        self._version_ = "API-4"
+        self._version_ = "API-5"
         self._loaded = False    # If true, this means the environment was successfully loaded
         self.proc1 = None       # The process that is started. If None, no process was started
         self.communicator = self.get_communicator(worker_id, base_port)
diff --git a/ml-agents/tests/mock_communicator.py b/ml-agents/tests/mock_communicator.py
index 296cc20067..43365d77c0 100755
--- a/ml-agents/tests/mock_communicator.py
+++ b/ml-agents/tests/mock_communicator.py
@@ -39,7 +39,7 @@ def initialize(self, inputs: UnityInput) -> UnityOutput:
         )
         rl_init = UnityRLInitializationOutput(
             name="RealFakeAcademy",
-            version="API-4",
+            version="API-5",
             log_path="",
             brain_parameters=[bp]
         )
diff --git a/ml-agents/tests/trainers/test_trainer_controller.py b/ml-agents/tests/trainers/test_trainer_controller.py
index fb99e5ed38..d7e870b71f 100644
--- a/ml-agents/tests/trainers/test_trainer_controller.py
+++ b/ml-agents/tests/trainers/test_trainer_controller.py
@@ -22,7 +22,7 @@ def dummy_start():
               "brainNames": ["RealFakeBrain"],
               "externalBrainNames": ["RealFakeBrain"],
               "logPath":"RealFakePath",
-              "apiNumber":"API-3",
+              "apiNumber":"API-5",
               "brainParameters": [{
                   "vectorObservationSize": 3,
                   "numStackedVectorObservations" : 2,