diff --git a/lib/bridge_client_lib.py b/lib/bridge_client_lib.py
index 14c12e2..4285c15 100644
--- a/lib/bridge_client_lib.py
+++ b/lib/bridge_client_lib.py
@@ -33,6 +33,28 @@ def _headers(token: str) -> dict[str, str]:
     }
 
 
+def _response_json(r: requests.Response) -> tuple[dict[str, Any] | None, str]:
+    """安全解析 JSON;失败返回 (None, 可读原因)."""
+    raw = (r.content or b"").strip()
+    if not raw:
+        return None, f"HTTP {r.status_code} 空响应"
+    try:
+        data = r.json()
+    except ValueError:
+        snippet = raw[:120].decode("utf-8", errors="replace").replace("\n", " ")
+        hint = ""
+        if r.status_code in (401, 403):
+            hint = ";检查 Bridge Token"
+        elif r.status_code == 404:
+            hint = ";客户端可能未部署 /api/hub/version(请先手动更新实例)"
+        elif snippet.lstrip().startswith("<"):
+            hint = ";收到 HTML(可能被登录页/反代拦截)"
+        return None, f"HTTP {r.status_code} 非 JSON{hint}: {snippet}"
+    if not isinstance(data, dict):
+        return None, f"HTTP {r.status_code} 响应不是对象"
+    return data, ""
+
+
 def fetch_one_snapshot(inst: dict[str, Any]) -> dict[str, Any]:
     base = (inst.get("base_url") or "").rstrip("/")
     token = (inst.get("bridge_token") or "").strip()
@@ -294,9 +316,9 @@ def fetch_client_version(inst: dict[str, Any]) -> dict[str, Any]:
             headers={"X-Hub-Token": token, "Accept": "application/json"},
             timeout=_timeout(),
         )
-        data = r.json() if r.content else {}
-        if not isinstance(data, dict):
-            out["msg"] = f"HTTP {r.status_code}"
+        data, err = _response_json(r)
+        if data is None:
+            out["msg"] = err or f"HTTP {r.status_code}"
             return out
         for key in ("sha", "short_sha", "branch", "dirty", "msg", "repo"):
             if key in data:
@@ -304,7 +326,7 @@ def fetch_client_version(inst: dict[str, Any]) -> dict[str, Any]:
         out["ok"] = bool(data.get("ok")) and r.status_code == 200
         out["online"] = out["ok"]
         if not out["ok"]:
-            out["msg"] = data.get("msg") or f"HTTP {r.status_code}"
+            out["msg"] = data.get("msg") or err or f"HTTP {r.status_code}"
         return out
     except requests.Timeout:
         out["msg"] = "超时"
@@ -333,14 +355,14 @@ def post_client_update(inst: dict[str, Any]) -> dict[str, Any]:
             json={},
             timeout=_timeout(),
         )
-        data = r.json() if r.content else {}
-        if not isinstance(data, dict):
-            data = {"ok": False, "msg": f"HTTP {r.status_code}"}
+        data, err = _response_json(r)
+        if data is None:
+            data = {"ok": False, "msg": err or f"HTTP {r.status_code}"}
         data["instance_id"] = inst.get("id")
         data["instance_name"] = inst.get("name")
-        if r.status_code >= 400 and "ok" not in data:
+        if r.status_code >= 400 and not data.get("ok"):
             data["ok"] = False
-            data.setdefault("msg", f"HTTP {r.status_code}")
+            data.setdefault("msg", err or f"HTTP {r.status_code}")
         return data
     except requests.Timeout:
         return {
@@ -370,12 +392,18 @@ def fetch_backup_list(inst: dict[str, Any]) -> dict[str, Any]:
             headers={"X-Hub-Token": token, "Accept": "application/json"},
             timeout=_timeout(),
         )
-        data = r.json() if r.content else {}
-        if isinstance(data, dict):
-            data.setdefault("instance_id", inst.get("id"))
-            data.setdefault("instance_name", inst.get("name"))
-            return data
-        return {"ok": False, "msg": f"HTTP {r.status_code}", "items": []}
+        data, err = _response_json(r)
+        if data is None:
+            return {
+                "ok": False,
+                "msg": err or f"HTTP {r.status_code}",
+                "items": [],
+                "instance_id": inst.get("id"),
+                "instance_name": inst.get("name"),
+            }
+        data.setdefault("instance_id", inst.get("id"))
+        data.setdefault("instance_name", inst.get("name"))
+        return data
     except Exception as e:
         return {
             "ok": False,
diff --git a/templates/settings.html b/templates/settings.html
index d6269af..226b905 100644
--- a/templates/settings.html
+++ b/templates/settings.html
@@ -183,7 +183,7 @@
 {% endblock %}
 {% block scripts %}
 <script src="{{ url_for('static', filename='settings_backup.js') }}?v=2"></script>
-<script src="{{ url_for('static', filename='settings_update.js') }}?v=3"></script>
+<script src="{{ url_for('static', filename='settings_update.js') }}?v=4"></script>
 <script>
   HubSettingsBackup.boot();
   HubSettingsUpdate.boot();