diff --git a/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/BackendUtil.java b/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/BackendUtil.java
index 987ec9a1b..26771c9d9 100644
--- a/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/BackendUtil.java
+++ b/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/BackendUtil.java
@@ -108,7 +108,8 @@ public static boolean tryHttpConnection(String host) {
             int responseCode = connection.getResponseCode();
             String responseMessage = connection.getResponseMessage();
             connection.disconnect();
-            if (200 == responseCode) {
+            if (responseCode < 500) {
+                // code greater than 500 means a server-side exception.
                 return true;
             }
             LOG.warn(