diff --git a/package.json b/package.json
index 003ea4c..cd6e5da 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "bitget-api",
-  "version": "2.3.0",
+  "version": "2.3.1",
   "description": "Node.js & JavaScript SDK for Bitget REST APIs & WebSockets, with TypeScript & end-to-end tests.",
   "main": "lib/index.js",
   "types": "lib/index.d.ts",
diff --git a/src/rest-client-v2.ts b/src/rest-client-v2.ts
index ce3a7ea..f5f5788 100644
--- a/src/rest-client-v2.ts
+++ b/src/rest-client-v2.ts
@@ -1262,7 +1262,7 @@ export class RestClientV2 extends BaseRestClient {
   }
 
   getFuturesContractConfig(params: {
-    symbol: string;
+    symbol?: string;
     productType: FuturesProductTypeV2;
   }): Promise<APIResponse<FuturesContractConfigV2[]>> {
     return this.get('/api/v2/mix/market/contracts', params);
diff --git a/src/util/BaseRestClient.ts b/src/util/BaseRestClient.ts
index dcf4057..9f407aa 100644
--- a/src/util/BaseRestClient.ts
+++ b/src/util/BaseRestClient.ts
@@ -92,6 +92,7 @@ export default abstract class BaseRestClient {
   constructor(
     restOptions: RestClientOptions = {},
     networkOptions: AxiosRequestConfig = {},
+    useDemoTrading: boolean = false,
   ) {
     this.options = {
       recvWindow: 5000,
@@ -110,6 +111,7 @@ export default abstract class BaseRestClient {
         'X-CHANNEL-API-CODE': 'hbnni',
         'Content-Type': 'application/json',
         locale: 'en-US',
+        ...(useDemoTrading ? { paptrading: '1' } : {}),
       },
     };