diff --git a/src/Error.ts b/src/Error.ts
index d8d3ae2..9ce0ce1 100644
--- a/src/Error.ts
+++ b/src/Error.ts
@@ -6,6 +6,8 @@ export class JSONRPCError extends Error {
   public message: string;
   public code: number;
   public data?: unknown;
+  // For transports that run over Fetch.
+  public response?: Response;
   constructor(message: string, code: number, data?: any) {
     super(message);
     this.message = message;
diff --git a/src/transports/EventEmitterTransport.ts b/src/transports/EventEmitterTransport.ts
index 9583581..e7679db 100644
--- a/src/transports/EventEmitterTransport.ts
+++ b/src/transports/EventEmitterTransport.ts
@@ -31,7 +31,9 @@ class EventEmitterTransport extends Transport {
       this.transportRequestManager.settlePendingRequest(notifications);
       return prom;
     } catch (e) {
-      const responseErr = new JSONRPCError(e.message, ERR_UNKNOWN, e);
+      const responseErr = e instanceof JSONRPCError
+        ? e
+        : new JSONRPCError(e.message, ERR_UNKNOWN, e);
       this.transportRequestManager.settlePendingRequest(notifications, responseErr);
       return Promise.reject(responseErr);
     }
diff --git a/src/transports/HTTPTransport.ts b/src/transports/HTTPTransport.ts
index 06b8f9c..df51db1 100644
--- a/src/transports/HTTPTransport.ts
+++ b/src/transports/HTTPTransport.ts
@@ -39,8 +39,9 @@ class HTTPTransport extends Transport {
     const notifications = getNotifications(data);
     const batch = getBatchRequests(data);
     const fetcher = this.injectedFetcher || fetch;
+    let result;
     try {
-      const result = await fetcher(this.uri, {
+      result = await fetcher(this.uri, {
         method: "POST",
         headers: this.headers,
         body: JSON.stringify(this.parseData(data)),
@@ -54,13 +55,18 @@ class HTTPTransport extends Transport {
       const body = await result.text();
       const responseErr = this.transportRequestManager.resolveResponse(body);
       if (responseErr) {
-        // requirements are that batch requuests are successfully resolved
+        // requirements are that batch requests are successfully resolved
         // this ensures that individual requests within the batch request are settled
         this.transportRequestManager.settlePendingRequest(batch, responseErr);
         return Promise.reject(responseErr);
       }
     } catch (e) {
-      const responseErr = new JSONRPCError(e.message, ERR_UNKNOWN, e);
+      const responseErr = e instanceof JSONRPCError
+        ? e
+        : new JSONRPCError(e.message, ERR_UNKNOWN, e);
+      responseErr.response = result
+        || (e?.response instanceof Response && e.response)
+        || undefined;
       this.transportRequestManager.settlePendingRequest(
         notifications,
         responseErr
diff --git a/src/transports/TransportRequestManager.ts b/src/transports/TransportRequestManager.ts
index 03d679f..a19b890 100644
--- a/src/transports/TransportRequestManager.ts
+++ b/src/transports/TransportRequestManager.ts
@@ -67,7 +67,9 @@ export class TransportRequestManager {
       }
       return this.resolveRes(data, emitError);
     } catch (e) {
-      const err = new JSONRPCError("Bad response format", ERR_UNKNOWN, payload);
+      const err = e instanceof JSONRPCError
+        ? e
+        : new JSONRPCError("Bad response format", ERR_UNKNOWN, payload);
       if (emitError) {
         this.transportEventChannel.emit("error", err);
       }
@@ -122,17 +124,19 @@ export class TransportRequestManager {
   private resolveRes(data: IJSONRPCNotificationResponse | IJSONRPCResponse, emitError: boolean): TransportResponse {
     const { id, error } = data;
 
-    const status = this.pendingRequest[id as string];
-    if (status) {
-      delete this.pendingRequest[id as string];
-      this.processResult(data, status);
-      this.transportEventChannel.emit("response", data as IJSONRPCResponse);
-      return;
-    }
     if (id === undefined && error === undefined) {
       this.transportEventChannel.emit("notification", data as IJSONRPCNotificationResponse);
       return;
     }
+    const status = this.pendingRequest[id as string];
+    if (status) {
+      delete this.pendingRequest[id as string];
+      if (error === undefined) {
+        this.processResult(data, status);
+        this.transportEventChannel.emit("response", data as IJSONRPCResponse);
+        return;
+      }
+    }
     let err;
     if (error) {
       err = convertJSONToRPCError(data);
diff --git a/src/transports/WebSocketTransport.ts b/src/transports/WebSocketTransport.ts
index 5727ddd..bebe6a7 100644
--- a/src/transports/WebSocketTransport.ts
+++ b/src/transports/WebSocketTransport.ts
@@ -33,8 +33,9 @@ class WebSocketTransport extends Transport {
       this.connection.send(JSON.stringify(this.parseData(data)));
       this.transportRequestManager.settlePendingRequest(notifications);
     } catch (err) {
-      const jsonError = new JSONRPCError((err as any).message, ERR_UNKNOWN, err);
-
+      const jsonError = err instanceof JSONRPCError
+        ? err
+        : new JSONRPCError(e.message, ERR_UNKNOWN, err);
       this.transportRequestManager.settlePendingRequest(notifications, jsonError);
       this.transportRequestManager.settlePendingRequest(getBatchRequests(data), jsonError);