diff --git a/pigx-common/pigx-common-core/src/main/java/com/pig4cloud/pigx/common/core/config/JacksonConfiguration.java b/pigx-common/pigx-common-core/src/main/java/com/pig4cloud/pigx/common/core/config/JacksonConfiguration.java
index cd9b6f222..a596a8ba2 100644
--- a/pigx-common/pigx-common-core/src/main/java/com/pig4cloud/pigx/common/core/config/JacksonConfiguration.java
+++ b/pigx-common/pigx-common-core/src/main/java/com/pig4cloud/pigx/common/core/config/JacksonConfiguration.java
@@ -82,6 +82,7 @@ public class JacksonConfiguration implements WebMvcConfigurer {
      * <li>yyyy-MM-dd -> LocalDate</li>
      * <li>yyyy-MM-dd HH:mm:ss -> LocalDateTime</li>
      * </ul>
+     *
      * @param registry
      */
     @Override
@@ -95,6 +96,7 @@ public class JacksonConfiguration implements WebMvcConfigurer {
 
     /**
      * 避免form 提交 context-type 不规范中文乱码
+     *
      * @return Filter
      */
     @Bean
@@ -119,14 +121,19 @@ public class JacksonConfiguration implements WebMvcConfigurer {
      * 替换策略：用 {@link ListIterator#set} 原地替换 Jackson 3 converter；找不到时把 Jackson 2
      * converter 插到队首作为 fallback。不做 clear，以免破坏 byte[]、String、multipart
      * 等其它默认 converter。
+     *
      * @param converters 消息转换器列表
      */
     @Override
     public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
         ObjectMapper objectMapper = objectMapperProvider.getIfAvailable();
         if (objectMapper == null) {
-            log.warn("ObjectMapper 不可用，跳过 Spring MVC Jackson 2 替换；保留 Spring Boot 默认 converter 链。");
-            return;
+            // 本类存在的唯一目的就是把 MVC 链路桥接回 Jackson 2，拿不到 Jackson 2 ObjectMapper
+            // 说明 jackson2 autoconfigure 未生效，属于环境配置错误。若静默降级到 Jackson 3，
+            // pigx-common-xss 的反序列化 XSS 清洗、Long->String、时间格式都会失效且难以察觉，
+            // 因此在启动期 fail-fast 暴露，而不是带病运行。
+            throw new IllegalStateException("Jackson 2 ObjectMapper 不可用，无法将 Spring MVC 桥接到 Jackson 2；"
+                    + "请检查 jackson2 autoconfigure 是否生效（XSS 清洗、Long 字符串化、时间格式均依赖于此）。");
         }
 
         org.springframework.http.converter.json.MappingJackson2HttpMessageConverter jackson2Converter =
@@ -134,9 +141,10 @@ public class JacksonConfiguration implements WebMvcConfigurer {
         ListIterator<HttpMessageConverter<?>> it = converters.listIterator();
         boolean replaced = false;
         while (it.hasNext()) {
-            if (it.next() instanceof JacksonJsonHttpMessageConverter) {
+            if (it.next().getClass() == JacksonJsonHttpMessageConverter.class) {
                 it.set(jackson2Converter);
                 replaced = true;
+                break;
             }
         }
         if (!replaced) {