diff --git a/src/fgai/dashboard.py b/src/fgai/dashboard.py
index b0e7fe8..9e5779c 100644
--- a/src/fgai/dashboard.py
+++ b/src/fgai/dashboard.py
@@ -274,6 +274,10 @@ def serve_dashboard(host: str, port: int, status_file: str, *, image_dir: str |
                     result = client.call_tool("list_streams", {})
                     content = result.get("result", {}).get("content", [])
                     text = next((item.get("text", "") for item in content if isinstance(item, dict)), "")
+                    if isinstance(result.get("result"), dict) and result["result"].get("isError"):
+                        raise RuntimeError(str(text or "Graylog list_streams failed"))
+                    if not text:
+                        raise RuntimeError("Graylog list_streams returned no text content")
                     streams = json.loads(text)
                     body = {"streams": streams, "selected": config.get("graylog_streams", [])}
                     self._send(200, "application/json", json.dumps(body).encode("utf-8"))