diff --git a/gns3server/handlers/api/iou_handler.py b/gns3server/handlers/api/iou_handler.py
index 3314e580..477d31d6 100644
--- a/gns3server/handlers/api/iou_handler.py
+++ b/gns3server/handlers/api/iou_handler.py
@@ -58,6 +58,8 @@ class IOUHandler:
 
         for name, value in request.json.items():
             if hasattr(vm, name) and getattr(vm, name) != value:
+                if name == "initial_config_content" and (vm.initial_config_content and len(vm.initial_config_content) > 0):
+                    continue
                 setattr(vm, name, value)
         response.set_status(201)
         response.json(vm)
diff --git a/gns3server/modules/iou/iou_vm.py b/gns3server/modules/iou/iou_vm.py
index 783b1357..b7214bd4 100644
--- a/gns3server/modules/iou/iou_vm.py
+++ b/gns3server/modules/iou/iou_vm.py
@@ -973,7 +973,7 @@ class IOUVM(BaseVM):
             if len(initial_config) == 0 and os.path.exists(initial_config_path):
                 return
 
-            with open(initial_config_path, "w+", encoding="utf-8") as f:
+            with open(initial_config_path, 'w+', encoding='utf-8') as f:
                 if len(initial_config) == 0:
                     f.write('')
                 else:
diff --git a/tests/handlers/api/test_iou.py b/tests/handlers/api/test_iou.py
index 643ebc34..ebc3c5d1 100644
--- a/tests/handlers/api/test_iou.py
+++ b/tests/handlers/api/test_iou.py
@@ -19,6 +19,7 @@ import pytest
 import os
 import stat
 import sys
+import uuid
 
 from tests.utils import asyncio_patch
 from unittest.mock import patch, MagicMock, PropertyMock
@@ -94,11 +95,32 @@ def test_iou_create_with_params(server, project, base_params):
 
     assert "initial-config.cfg" in response.json["initial_config"]
     with open(initial_config_file(project, response.json)) as f:
-        assert f.read() == params["initial_config_content"]
+        assert f.read() == "hostname test"
 
     assert "iourc" in response.json["iourc_path"]
 
 
+def test_iou_create_initial_config_already_exist(server, project, base_params):
+    """We don't erase an initial config if already exist at project creation"""
+
+    vm_id = str(uuid.uuid4())
+    initial_config_file_path = initial_config_file(project, {'vm_id': vm_id})
+    with open(initial_config_file_path, 'w+') as f:
+        f.write("echo hello")
+
+    params = base_params
+    params["vm_id"] = vm_id
+    params["initial_config_content"] = "hostname test"
+
+    response = server.post("/projects/{project_id}/iou/vms".format(project_id=project.id), params, example=True)
+    assert response.status == 201
+    assert response.route == "/projects/{project_id}/iou/vms"
+
+    assert "initial-config.cfg" in response.json["initial_config"]
+    with open(initial_config_file(project, response.json)) as f:
+        assert f.read() == "echo hello"
+
+
 def test_iou_get(server, project, vm):
     response = server.get("/projects/{project_id}/iou/vms/{vm_id}".format(project_id=vm["project_id"], vm_id=vm["vm_id"]), example=True)
     assert response.status == 200