diff --git a/src/renderer/src/i18n/locales/en-us.json b/src/renderer/src/i18n/locales/en-us.json
index 02645faa69..bc63d6132c 100644
--- a/src/renderer/src/i18n/locales/en-us.json
+++ b/src/renderer/src/i18n/locales/en-us.json
@@ -447,6 +447,7 @@
         "504": "Gateway timeout. Please try again later"
       },
       "model.exists": "Model already exists",
+      "missing_user_message": "Cannot switch model response: The original user message has been deleted. Please send a new message to get a response with this model.",
       "no_api_key": "API key is not configured",
       "provider_disabled": "Model provider is not enabled",
       "render": {
diff --git a/src/renderer/src/i18n/locales/ja-jp.json b/src/renderer/src/i18n/locales/ja-jp.json
index f2f802cd26..4180e7b20e 100644
--- a/src/renderer/src/i18n/locales/ja-jp.json
+++ b/src/renderer/src/i18n/locales/ja-jp.json
@@ -447,6 +447,7 @@
         "504": "ゲートウェイタイムアウトが発生しました。後でもう一度試してください"
       },
       "model.exists": "モデルが既に存在します",
+      "missing_user_message": "モデル応答を切り替えられません：元のユーザーメッセージが削除されました。このモデルで応答を得るには、新しいメッセージを送信してください",
       "no_api_key": "APIキーが設定されていません",
       "provider_disabled": "モデルプロバイダーが有効になっていません",
       "render": {
diff --git a/src/renderer/src/i18n/locales/ru-ru.json b/src/renderer/src/i18n/locales/ru-ru.json
index b5b5bfbd11..9efc0c7cc0 100644
--- a/src/renderer/src/i18n/locales/ru-ru.json
+++ b/src/renderer/src/i18n/locales/ru-ru.json
@@ -447,6 +447,7 @@
         "504": "Серверная ошибка. Пожалуйста, попробуйте позже"
       },
       "model.exists": "Модель уже существует",
+      "missing_user_message": "Невозможно изменить модель ответа: исходное сообщение пользователя было удалено. Пожалуйста, отправьте новое сообщение, чтобы получить ответ от этой модели",
       "no_api_key": "Ключ API не настроен",
       "provider_disabled": "Провайдер моделей не включен",
       "render": {
diff --git a/src/renderer/src/i18n/locales/zh-cn.json b/src/renderer/src/i18n/locales/zh-cn.json
index 3fec012014..76f1bfcee3 100644
--- a/src/renderer/src/i18n/locales/zh-cn.json
+++ b/src/renderer/src/i18n/locales/zh-cn.json
@@ -447,6 +447,7 @@
         "504": "网关超时，请稍后再试"
       },
       "model.exists": "模型已存在",
+      "missing_user_message": "无法切换模型响应：原始用户消息已被删除。请发送新消息以获取此模型的响应",
       "no_api_key": "API 密钥未配置",
       "provider_disabled": "模型提供商未启用",
       "render": {
diff --git a/src/renderer/src/i18n/locales/zh-tw.json b/src/renderer/src/i18n/locales/zh-tw.json
index 9e1a74d5e8..531210b660 100644
--- a/src/renderer/src/i18n/locales/zh-tw.json
+++ b/src/renderer/src/i18n/locales/zh-tw.json
@@ -447,6 +447,7 @@
         "504": "閘道器超時，請稍後再試"
       },
       "model.exists": "模型已存在",
+      "missing_user_message": "無法切換模型回應：原始用戶訊息已被刪除。請發送新訊息以獲得此模型回應。",
       "no_api_key": "API 金鑰未設定",
       "provider_disabled": "模型供應商未啟用",
       "render": {
diff --git a/src/renderer/src/store/thunk/messageThunk.ts b/src/renderer/src/store/thunk/messageThunk.ts
index eaf658aa13..0360022a54 100644
--- a/src/renderer/src/store/thunk/messageThunk.ts
+++ b/src/renderer/src/store/thunk/messageThunk.ts
@@ -1165,6 +1165,29 @@ export const regenerateAssistantResponseThunk =
       // 1. Use selector to get all messages for the topic
       const allMessagesForTopic = selectMessagesForTopic(state, topicId)
 
+      const askId = assistantMessageToRegenerate.askId
+
+      if (!askId) {
+        console.error(
+          `[appendAssistantResponseThunk] Existing assistant message ${assistantMessageToRegenerate.id} does not have an askId.`
+        )
+        return // Stop if askId is missing
+      }
+
+      if (!state.messages.entities[askId]) {
+        console.error(
+          `[appendAssistantResponseThunk] Original user query (askId: ${askId}) not found in entities. Cannot create assistant response without corresponding user message.`
+        )
+
+        // Show error popup instead of creating error message block
+        window.message.error({
+          content: t('error.missing_user_message'),
+          key: 'missing-user-message-error'
+        })
+
+        return
+      }
+
       // 2. Find the original user query (Restored Logic)
       const originalUserQuery = allMessagesForTopic.find((m) => m.id === assistantMessageToRegenerate.askId)
       if (!originalUserQuery) {
@@ -1375,10 +1398,17 @@ export const appendAssistantResponseThunk =
 
       // (Optional but recommended) Verify the original user query exists
       if (!state.messages.entities[askId]) {
-        console.warn(
-          `[appendAssistantResponseThunk] Original user query (askId: ${askId}) not found in entities. Proceeding, but state might be inconsistent.`
+        console.error(
+          `[appendAssistantResponseThunk] Original user query (askId: ${askId}) not found in entities. Cannot create assistant response without corresponding user message.`
         )
-        // Decide whether to proceed or return based on requirements
+
+        // Show error popup instead of creating error message block
+        window.message.error({
+          content: t('error.missing_user_message'),
+          key: 'missing-user-message-error'
+        })
+
+        return
       }
 
       // 2. Create the new assistant message stub