diff --git a/runner-core/src/main/java/org/apache/apisix/plugin/runner/handler/RpcCallHandler.java b/runner-core/src/main/java/org/apache/apisix/plugin/runner/handler/RpcCallHandler.java
index 06095ed..50eca38 100644
--- a/runner-core/src/main/java/org/apache/apisix/plugin/runner/handler/RpcCallHandler.java
+++ b/runner-core/src/main/java/org/apache/apisix/plugin/runner/handler/RpcCallHandler.java
@@ -180,6 +180,10 @@ private void handleHttpRespCall(ChannelHandlerContext ctx, PostRequest request)
 
         PluginFilterChain chain = conf.getChain();
 
+        // here we pre-read parameters in the resp to
+        // prevent confusion over the read/write index of the resp.
+        preReadPostReq();
+
         if (Objects.isNull(chain) || 0 == chain.getFilters().size()) {
             ChannelFuture future = ctx.writeAndFlush(postResp);
             future.addListeners(ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE);
@@ -328,6 +332,11 @@ private void preReadReq() {
         currReq.getSourceIP();
     }
 
+    private void preReadPostReq() {
+        postReq.getUpstreamHeaders();
+        postReq.getUpstreamStatusCode();
+    }
+
     private void errorHandle(ChannelHandlerContext ctx, int code) {
         A6ErrResponse errResponse = new A6ErrResponse(code);
         ctx.writeAndFlush(errResponse);