diff --git a/gateway/run.py b/gateway/run.py
index 4201dde1ca58..1c6a8a839738 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -7823,10 +7823,24 @@ class GatewayRunner(GatewayAuthorizationMixin, GatewayKanbanWatchersMixin, Gatew
         Returns True if at least one adapter connected successfully.
         """
         logger.info("Starting Hermes Gateway...")
-        # Enable faulthandler at gateway start so that SIGUSR2 (or an
-        # internal watchdog) can dump all thread and task stacks to stderr
-        # for post-mortem diagnosis of event-loop freezes (#70344).
-        faulthandler.enable()
+        # Enable faulthandler for stack dumps on freezes/crashes (#70344).
+        # Falls back to a log file when sys.stderr is None (Windows VBS /
+        # pythonw / detached service) — otherwise the gateway would die
+        # here and take every adapter offline. See #71671.
+        try:
+            faulthandler.enable()
+        except (RuntimeError, ValueError, OSError):
+            try:
+                _fh_log_dir = getattr(self.config, "log_dir", None) or os.path.join(
+                    os.environ.get("HERMES_HOME", str(Path.home() / ".hermes")),
+                    "logs",
+                )
+                os.makedirs(_fh_log_dir, exist_ok=True)
+                _fh_enable_path = os.path.join(_fh_log_dir, "gateway_faulthandler.log")
+                _fh_enable_file = open(_fh_enable_path, "a", encoding="utf-8")
+                faulthandler.enable(file=_fh_enable_file, all_threads=True)
+            except Exception:
+                logger.debug("faulthandler.enable() unavailable", exc_info=True)
         # Also dump stacks to a rotating file for off-line analysis when
         # the gateway is running under a service manager that doesn't
         # capture stderr.