使用AWS CDK创建Lex Bot V2报错：en_US区域缺少回退意图

问题描述 #

使用AWS CDK创建Lex Bot V2时，代码如下：

const bot = new lex.CfnBot(this, "MyLexBot", {
  name: "MyBot",
  dataPrivacy: { ChildDirected: false },
  idleSessionTtlInSeconds: 300,
  roleArn: lexRole.roleArn,
  botLocales: [
    {
      localeId: "en_US",
      nluConfidenceThreshold: 0,
      intents: [
        {
          name: "OrderIntent",
          sampleUtterances: [
            { utterance: "hello" },
            { utterance: "I want to order" },
            { utterance: "Can I place an order?" },
          ],
          fulfillmentCodeHook: { enabled: false },
        },
        {
          name: "CustomFallbackIntent",
          description: "Default fallback intent",
          parentIntentSignature: "AMAZON.FallbackIntent",
          fulfillmentCodeHook: { enabled: false },
        },
      ],
    },
  ],

持续收到报错：

Couldn't import a locale. Locale ‘en_US’ in the zip file doesn't contain a fallback intent. Provide a fallback intent for the locale, then try your request again.

尝试创建不含意图的botLocales，问题依旧。

解决方案 #

核心修复：标记自定义fallback意图 #

Lex V2要求每个locale必须有一个明确标记为fallback的意图，你的代码中虽定义了继承AMAZON.FallbackIntent的自定义意图，但未添加isFallback: true属性，导致Lex无法识别它为fallback意图。修改后的代码如下：

const bot = new lex.CfnBot(this, "MyLexBot", {
  name: "MyBot",
  dataPrivacy: { ChildDirected: false },
  idleSessionTtlInSeconds: 300,
  roleArn: lexRole.roleArn,
  botLocales: [
    {
      localeId: "en_US",
      nluConfidenceThreshold: 0.5, // 建议设置合理阈值，0易引发匹配异常
      intents: [
        {
          name: "OrderIntent",
          sampleUtterances: [
            { utterance: "hello" },
            { utterance: "I want to order" },
            { utterance: "Can I place an order?" },
          ],
          fulfillmentCodeHook: { enabled: false },
        },
        {
          name: "CustomFallbackIntent",
          description: "Default fallback intent",
          parentIntentSignature: "AMAZON.FallbackIntent",
          isFallback: true, // 关键：添加此属性标记为fallback意图
          fulfillmentCodeHook: { enabled: false },
        },
      ],
    },
  ],
});

额外排查点 #

• 确保每个bot locale的intents列表中，仅有一个标记为isFallback: true的意图。
• 检查Lex角色权限，确保拥有配置bot意图的相关权限。
• 若使用旧版CDK，需升级至支持Lex V2 isFallback属性的版本。

内容的提问来源于stack exchange，提问作者ZunX