diff --git a/diracx-routers/src/diracx/routers/__init__.py b/diracx-routers/src/diracx/routers/__init__.py
index baa99784..ef464d24 100644
--- a/diracx-routers/src/diracx/routers/__init__.py
+++ b/diracx-routers/src/diracx/routers/__init__.py
@@ -54,7 +54,7 @@
 logger = logging.getLogger(__name__)
 
 
-DIRACX_MIN_CLIENT_VERSION = "0.0.1"
+DIRACX_MIN_CLIENT_VERSION = "0.0.1a1"
 
 ###########################################3
 
@@ -464,12 +464,15 @@ def __init__(self, app: FastAPI):
 
     async def dispatch(self, request: Request, call_next) -> Response:
         client_version = request.headers.get("DiracX-Client-Version")
+
         if client_version and self.is_version_too_old(client_version):
             # When comes from Swagger or Web, there is no client version header.
             # This is not managed here.
-            raise HTTPException(
+            # Return a JSONResponse because the HTTPException
+            # is not handled nicely in the middleware
+            return JSONResponse(
                 status_code=HTTPStatus.UPGRADE_REQUIRED,
-                detail=f"Client version ({client_version}) not recent enough (>= {self.min_client_version}). Upgrade.",
+                content=f"Client version ({client_version}) not recent enough (>= {self.min_client_version}). Upgrade.",
             )
 
         response = await call_next(request)