diff --git a/src/aleph/vm/orchestrator/views/__init__.py b/src/aleph/vm/orchestrator/views/__init__.py
index 994476cba..243138624 100644
--- a/src/aleph/vm/orchestrator/views/__init__.py
+++ b/src/aleph/vm/orchestrator/views/__init__.py
@@ -65,9 +65,12 @@ async def run_code_from_path(request: web.Request) -> web.Response:
     path = request.match_info["suffix"]
     path = path if path.startswith("/") else f"/{path}"
 
-    message_ref = ItemHash(request.match_info["ref"])
-    pool: VmPool = request.app["vm_pool"]
-    return await run_code_on_request(message_ref, path, pool, request)
+    try:
+        message_ref = ItemHash(request.match_info["ref"])
+        pool: VmPool = request.app["vm_pool"]
+        return await run_code_on_request(message_ref, path, pool, request)
+    except UnknownHashError as error:
+        raise HTTPNotFound(reason="Invalid message reference") from error
 
 
 async def run_code_from_hostname(request: web.Request) -> web.Response:
@@ -100,6 +103,8 @@ async def run_code_from_hostname(request: web.Request) -> web.Response:
                 logger.debug(f"Using DNS TXT record to obtain '{message_ref}'")
             except aiodns.error.DNSError as error:
                 raise HTTPNotFound(reason="Invalid message reference") from error
+            except UnknownHashError as error:
+                raise HTTPNotFound(reason="Invalid message reference") from error
 
     pool = request.app["vm_pool"]
     return await run_code_on_request(message_ref, path, pool, request)