diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index ba526354a3..c56fc1e39e 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -5274,12 +5274,19 @@ def _warn_stale_dashboard_processes() -> None:
 
     try:
         if sys.platform == "win32":
+            # wmic emits text in the system code page (e.g. cp936 on zh-CN
+            # locales), not UTF-8. Without an explicit encoding, Python's
+            # default UTF-8 decoder crashes the subprocess reader thread
+            # with UnicodeDecodeError, leaving result.stdout=None and the
+            # subsequent .split() call crashing `hermes update` with an
+            # AttributeError on Windows non-UTF-8 locales (#17049).
             result = subprocess.run(
                 ["wmic", "process", "get", "ProcessId,CommandLine",
                  "/FORMAT:LIST"],
                 capture_output=True, text=True, timeout=10,
+                encoding="utf-8", errors="ignore",
             )
-            if result.returncode != 0:
+            if result.returncode != 0 or result.stdout is None:
                 return
             current_cmd = ""
             for line in result.stdout.split("\n"):
diff --git a/tests/hermes_cli/test_update_stale_dashboard.py b/tests/hermes_cli/test_update_stale_dashboard.py
index 20c5eee98c..b36f9e5a49 100644
--- a/tests/hermes_cli/test_update_stale_dashboard.py
+++ b/tests/hermes_cli/test_update_stale_dashboard.py
@@ -175,3 +175,57 @@ class TestWarnStaleDashboardProcesses:
         output = capsys.readouterr().out
         assert "PID 99999" not in output
         assert "PID 12345" in output
+
+
+class TestWindowsWmicEncoding:
+    """Regression tests for #17049 — the Windows wmic branch must not crash
+    `hermes update` on non-UTF-8 system locales (e.g. cp936 on zh-CN).
+    """
+
+    def test_wmic_invoked_with_utf8_ignore_errors(self):
+        """The wmic subprocess.run call must pass encoding='utf-8' and
+        errors='ignore' so the subprocess reader thread cannot raise
+        UnicodeDecodeError on non-UTF-8 wmic output."""
+        with patch("hermes_cli.main.sys") as mock_sys, \
+                patch("subprocess.run") as mock_run:
+            mock_sys.platform = "win32"
+            # Provide a minimal valid wmic /FORMAT:LIST response.
+            mock_run.return_value = MagicMock(
+                returncode=0,
+                stdout=(
+                    "CommandLine=python -m hermes_cli.main dashboard\n"
+                    "ProcessId=12345\n"
+                ),
+                stderr="",
+            )
+            _warn_stale_dashboard_processes()
+
+        assert mock_run.called, "subprocess.run was not invoked"
+        kwargs = mock_run.call_args.kwargs
+        assert kwargs.get("encoding") == "utf-8", (
+            "encoding kwarg must be 'utf-8' so wmic output is decoded "
+            "deterministically rather than via the implicit reader-thread "
+            "default that crashes on non-UTF-8 locales (#17049)."
+        )
+        assert kwargs.get("errors") == "ignore", (
+            "errors kwarg must be 'ignore' so undecodable bytes don't take "
+            "down the reader thread (#17049)."
+        )
+
+    def test_wmic_returns_none_stdout_does_not_crash(self, capsys):
+        """If subprocess.run returns successfully but stdout is None — which
+        is what Python 3.11 leaves behind when the reader thread silently
+        crashed on UnicodeDecodeError before this fix landed — the warning
+        must short-circuit instead of raising AttributeError on
+        ``None.split('\\n')`` and aborting `hermes update` (#17049)."""
+        with patch("hermes_cli.main.sys") as mock_sys, \
+                patch("subprocess.run") as mock_run:
+            mock_sys.platform = "win32"
+            mock_run.return_value = MagicMock(
+                returncode=0, stdout=None, stderr=""
+            )
+            # Must not raise.
+            _warn_stale_dashboard_processes()
+
+        output = capsys.readouterr().out
+        assert "dashboard process" not in output