diff --git a/apps/web/src/components/approval/live-approval-panel.tsx b/apps/web/src/components/approval/live-approval-panel.tsx
index f3c06af7d..8cce5a6b9 100644
--- a/apps/web/src/components/approval/live-approval-panel.tsx
+++ b/apps/web/src/components/approval/live-approval-panel.tsx
@@ -188,6 +188,8 @@ export function LiveApprovalPanel({
       }
     } else {
       setSigningStates((prev) => ({ ...prev, [id]: 'error' }))
+      // 🔴 Phase 22 P0: 新增錯誤 Toast 提示
+      toast.error('簽核失敗，請檢查網路連線或重新整理頁面')
       setTimeout(() => {
         setSigningStates((prev) => {
           const next = { ...prev }
@@ -360,6 +362,18 @@ export function LiveApprovalPanel({
                 </div>
               </div>
             )}
+
+            {/* 🔴 Phase 22 P0: Error Overlay */}
+            {signingStates[approval.id] === 'error' && (
+              <div className="absolute inset-0 flex items-center justify-center bg-status-critical/20 rounded-xl">
+                <div className="text-center">
+                  <StatusOrb status="critical" size="lg" glow />
+                  <p className="mt-2 text-status-critical font-mono font-semibold">
+                    {tCommon('error')}
+                  </p>
+                </div>
+              </div>
+            )}
           </div>
         )})}