diff --git a/app/orchestrator.py b/app/orchestrator.py
index 4c096f99..c1e9b6c4 100644
--- a/app/orchestrator.py
+++ b/app/orchestrator.py
@@ -1907,10 +1907,17 @@ def _check_proxy_binds(working_dir: str, extra_paths: list[str]) -> None:
     """Refuse, with the line to paste, an update the proxy would not let bind its folders."""
     compose_dir = os.getenv("CASHPILOT_COMPOSE_DIR", "").strip().rstrip("/")
     if compose_dir != working_dir.rstrip("/"):
+        # working_dir is the path Compose itself ran in. Under a webhook or a
+        # deployer container (Portainer and the like) that path is inside the
+        # deployer and may not exist on this host; the helper binds it as is,
+        # so no other value would work either: the deployer has to update.
         raise SelfUpdateUnavailable(
-            "The update helper needs your compose folder, and the Docker socket proxy lets "
-            "containers bind only the folders it was told about. Add this line to the .env "
-            f"next to your compose file, then run docker compose up -d once: "
+            f"The update helper needs your compose folder, which Docker Compose recorded as "
+            f"{working_dir}, and the Docker socket proxy lets containers bind only the folders "
+            "it was told about. If Compose runs inside another container for you (a webhook, "
+            "Portainer or another deployer), that path is inside it, not on this host: update "
+            "the stack from your deployer instead. Otherwise add this line to the .env next to "
+            "your compose file, then run docker compose up -d once: "
             f"{COMPOSE_DIR_ENV}={working_dir}"
         )
     roots = _proxy_bind_roots()
diff --git a/tests/test_socket_proxy.py b/tests/test_socket_proxy.py
index b0e24499..ba45cd62 100644
--- a/tests/test_socket_proxy.py
+++ b/tests/test_socket_proxy.py
@@ -611,6 +611,25 @@ def test_proxied_a_compose_folder_the_proxy_does_not_know_is_refused_with_the_li
     client.containers.run.assert_not_called()
 
 
+def test_proxied_under_a_deployer_container_the_refusal_does_not_pass_its_path_off_as_the_hosts(monkeypatch):
+    """Compose run by a webhook or Portainer records the deployer's own path
+    (/data/compose/12), which need not exist on the host. The advice must say
+    so and send the operator to the deployer, not only to that path."""
+    _proxied_env(monkeypatch, compose_dir="")
+    labels = {**tuf._COMPOSE_LABELS, "com.docker.compose.project.working_dir": "/data/compose/12"}
+    client = tuf._fake_docker(me=tuf._fake_container(labels=labels))
+    tuf._wire_runs(client)
+    with (
+        patch.object(orchestrator, "_get_client", return_value=client),
+        pytest.raises(orchestrator.SelfUpdateUnavailable) as refused,
+    ):
+        orchestrator.spawn_self_update()
+    message = str(refused.value)
+    assert "recorded as /data/compose/12" in message
+    assert "not on this host" in message and "update the stack from your deployer" in message
+    client.containers.run.assert_not_called()
+
+
 def test_proxied_a_trailing_slash_is_the_same_folder(monkeypatch):
     _proxied_env(monkeypatch, compose_dir="/srv/cashpilot/")
     client, result = _run_update()