diff --git a/data-agent-management/src/main/java/com/alibaba/cloud/ai/dataagent/workflow/node/SqlExecuteNode.java b/data-agent-management/src/main/java/com/alibaba/cloud/ai/dataagent/workflow/node/SqlExecuteNode.java
index 91c760a5c..90eb2ed36 100644
--- a/data-agent-management/src/main/java/com/alibaba/cloud/ai/dataagent/workflow/node/SqlExecuteNode.java
+++ b/data-agent-management/src/main/java/com/alibaba/cloud/ai/dataagent/workflow/node/SqlExecuteNode.java
@@ -152,7 +152,9 @@ private Map<String, Object> executeSqlQuery(OverAllState state, Integer currentS
 			.flatMapMany(executed -> Flux.concat(baseResultResponses(executed.resultSet()),
 					chartUpdateResponses(state, executed.resultSet())))
 			.onErrorResume(e -> {
-				String errorMessage = e.getMessage();
+				// NPE / StackOverflowError and several JDBC wrappers carry a null message;
+				// fall back to the exception type so the user never sees the literal "null"
+				String errorMessage = StringUtils.isNotBlank(e.getMessage()) ? e.getMessage() : e.getClass().getName();
 				log.error("SQL execution failed - SQL as follows: \n {} \n ", sqlQuery, e);
 				result.put(SQL_REGENERATE_REASON, SqlRetryDto.sqlExecute(errorMessage));
 				return Flux.just(ChatResponseUtil.createResponse("SQL执行失败: " + errorMessage));
diff --git a/data-agent-management/src/test/java/com/alibaba/cloud/ai/dataagent/workflow/node/sql/SqlExecuteNodeTest.java b/data-agent-management/src/test/java/com/alibaba/cloud/ai/dataagent/workflow/node/sql/SqlExecuteNodeTest.java
index 0b741b8bc..547eb33ff 100644
--- a/data-agent-management/src/test/java/com/alibaba/cloud/ai/dataagent/workflow/node/sql/SqlExecuteNodeTest.java
+++ b/data-agent-management/src/test/java/com/alibaba/cloud/ai/dataagent/workflow/node/sql/SqlExecuteNodeTest.java
@@ -237,6 +237,26 @@ void apply_sqlExecutionError_setsRetryReason() throws Exception {
 		assertFalse(execution.finalResult().containsKey(PLAN_CURRENT_STEP));
 	}
 
+	@Test
+	void apply_sqlExecutionErrorWithoutMessage_doesNotLeakNullIntoUserFacingText() throws Exception {
+		OverAllState state = createTestState();
+		setupBasicState(state);
+		setupBasicMocks();
+
+		// NPE / StackOverflowError and several JDBC wrappers carry a null message
+		when(accessor.executeSqlAndReturnObject(any(), any())).thenThrow(new RuntimeException((String) null));
+
+		NodeExecution execution = execute(sqlExecuteNode.apply(state), SQL_EXECUTE_NODE_OUTPUT);
+
+		String streamed = execution.streamedText();
+		assertFalse(streamed.contains("null"),
+				"user-facing text must not leak the literal 'null', was: " + streamed);
+		assertTrue(streamed.contains("SQL执行失败"), "failure notice must still be emitted, was: " + streamed);
+		SqlRetryDto retryReason = (SqlRetryDto) execution.finalResult().get(SQL_REGENERATE_REASON);
+		assertNotNull(retryReason);
+		assertTrue(retryReason.sqlExecuteFail());
+	}
+
 	@Test
 	void apply_connectionFailure_throwsException() throws Exception {
 		OverAllState state = createTestState();