diff --git a/lib/Server.js b/lib/Server.js
index ab7b345960..1840b33e7c 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -2040,6 +2040,15 @@ class Server {
         if (proxyConfig.router) {
           return createProxyMiddleware(proxyConfig);
         }
+
+        // TODO improve me after drop `bypass` to always generate error when configuration is bad
+        if (!proxyConfig.bypass) {
+          util.deprecate(
+            () => {},
+            `Invalid proxy configuration:\n\n${JSON.stringify(proxyConfig, null, 2)}\n\nThe use of proxy object notation as proxy routes has been removed.\nPlease use the 'router' or 'context' options. Read more at https://github.com/chimurai/http-proxy-middleware/tree/v2.0.6#http-proxy-middleware-options`,
+            "DEP_WEBPACK_DEV_SERVER_PROXY_ROUTES_ARGUMENT",
+          )();
+        }
       };
 
       /**
@@ -2090,12 +2099,15 @@ class Server {
 
             if (newProxyConfig !== proxyConfig) {
               proxyConfig = newProxyConfig;
+
               const socket = req.socket != null ? req.socket : req.connection;
               // @ts-ignore
               const server = socket != null ? socket.server : null;
+
               if (server) {
                 server.removeAllListeners("close");
               }
+
               proxyMiddleware =
                 /** @type {RequestHandler} */
                 (getProxyMiddleware(proxyConfig));
@@ -2110,7 +2122,7 @@ class Server {
           if (isByPassFuncDefined) {
             util.deprecate(
               () => {},
-              "Using the 'bypass' option is deprecated. Please use the 'router' and 'context' options. Read more at https://github.com/chimurai/http-proxy-middleware/tree/v2.0.6#http-proxy-middleware-options",
+              "Using the 'bypass' option is deprecated. Please use the 'router' or 'context' options. Read more at https://github.com/chimurai/http-proxy-middleware/tree/v2.0.6#http-proxy-middleware-options",
               "DEP_WEBPACK_DEV_SERVER_PROXY_BYPASS_ARGUMENT",
             )();
           }
diff --git a/test/server/proxy-option.test.js b/test/server/proxy-option.test.js
index 15ff236953..d894fdae08 100644
--- a/test/server/proxy-option.test.js
+++ b/test/server/proxy-option.test.js
@@ -238,7 +238,7 @@ describe("proxy option", () => {
         const lastCall = utilSpy.mock.calls[utilSpy.mock.calls.length - 1];
 
         expect(lastCall[1]).toEqual(
-          "Using the 'bypass' option is deprecated. Please use the 'router' and 'context' options. Read more at https://github.com/chimurai/http-proxy-middleware/tree/v2.0.6#http-proxy-middleware-options",
+          "Using the 'bypass' option is deprecated. Please use the 'router' or 'context' options. Read more at https://github.com/chimurai/http-proxy-middleware/tree/v2.0.6#http-proxy-middleware-options",
         );
         expect(lastCall[2]).toEqual(
           "DEP_WEBPACK_DEV_SERVER_PROXY_BYPASS_ARGUMENT",