diff --git a/netx_api/ume_client.py b/netx_api/ume_client.py
index ef8c512..c8b2cb1 100644
--- a/netx_api/ume_client.py
+++ b/netx_api/ume_client.py
@@ -175,10 +175,10 @@ class UMEClient:
         return headers
 
     def _client(self) -> httpx.Client:
-        # Force HTTP/1.1 (disable HTTP/2) due to UME server compatibility issues.
-        # httpx defaults to HTTP/1.1 unless http2=True, but some environments still
-        # negotiate/behave unexpectedly; be explicit here.
-        return httpx.Client(verify=self.verify_tls, timeout=self.timeout_s, http2=False)
+        # Use explicit HTTPTransport to keep behavior consistent with onsite validation.
+        # In this mode, requests run over HTTP/1.1 and avoid HTTP/2 negotiation issues.
+        transport = httpx.HTTPTransport()
+        return httpx.Client(verify=self.verify_tls, timeout=self.timeout_s, transport=transport)
 
     def _extract_token_and_ttl(self, payload: dict[str, Any]) -> tuple[str, int | None]:
         token = ""
diff --git a/web/src/pages/UmePage.tsx b/web/src/pages/UmePage.tsx
index 2dcdec4..21c2997 100644
--- a/web/src/pages/UmePage.tsx
+++ b/web/src/pages/UmePage.tsx
@@ -18,6 +18,7 @@ function toIsoNoMs(d: Date): string {
 
 export function UmePage() {
   const queryClient = useQueryClient();
+  const [tokenOpError, setTokenOpError] = useState("");
   const [syncPage, setSyncPage] = useState(1);
   const [syncPageSize, setSyncPageSize] = useState(20);
   const [neKeyword, setNeKeyword] = useState("");
@@ -71,15 +72,31 @@ export function UmePage() {
   });
   const tokenRefreshMutation = useMutation({
     mutationFn: refreshUmeToken,
-    onSuccess: async () => {
+    onSuccess: async (res) => {
+      if (!res?.ok) {
+        setTokenOpError(String(res.error || res.error_kind || "token_refresh_failed"));
+      } else {
+        setTokenOpError("");
+      }
       await queryClient.invalidateQueries({ queryKey: ["umeTokenStatus"] });
     },
+    onError: (err) => {
+      setTokenOpError(String(err));
+    },
   });
   const tokenDisconnectMutation = useMutation({
     mutationFn: disconnectUmeToken,
-    onSuccess: async () => {
+    onSuccess: async (res) => {
+      if (!res?.ok) {
+        setTokenOpError(String(res.error || res.error_kind || "token_disconnect_failed"));
+      } else {
+        setTokenOpError("");
+      }
       await queryClient.invalidateQueries({ queryKey: ["umeTokenStatus"] });
     },
+    onError: (err) => {
+      setTokenOpError(String(err));
+    },
   });
 
   const tokenExpiresIn = Number(tokenStatusQuery.data?.expires_in_s || 0);
@@ -151,9 +168,9 @@ export function UmePage() {
               断开 token
             </button>
           </div>
-          {(tokenRefreshMutation.error || tokenDisconnectMutation.error) && (
+          {(tokenOpError || tokenRefreshMutation.error || tokenDisconnectMutation.error) && (
             <div className="pill pill--high">
-              操作失败: {String(tokenRefreshMutation.error || tokenDisconnectMutation.error)}
+              操作失败: {tokenOpError || String(tokenRefreshMutation.error || tokenDisconnectMutation.error)}
             </div>
           )}
         </article>