diff --git a/packages/playwright-core/src/client/android.ts b/packages/playwright-core/src/client/android.ts
index 296a596977..07912bfbdd 100644
--- a/packages/playwright-core/src/client/android.ts
+++ b/packages/playwright-core/src/client/android.ts
@@ -76,7 +76,7 @@ export class Android extends ChannelOwner<channels.AndroidChannel> implements ap
       connection.on('close', closePipe);
 
       let device: AndroidDevice;
-      let closeError: Error | undefined;
+      let closeError: string | undefined;
       const onPipeClosed = () => {
         device?._didClose();
         connection.close(closeError);
@@ -88,7 +88,7 @@ export class Android extends ChannelOwner<channels.AndroidChannel> implements ap
         try {
           connection!.dispatch(message);
         } catch (e) {
-          closeError = e;
+          closeError = String(e);
           closePipe();
         }
       });
diff --git a/packages/playwright-core/src/client/browserType.ts b/packages/playwright-core/src/client/browserType.ts
index 2e1e12a529..9932050d3e 100644
--- a/packages/playwright-core/src/client/browserType.ts
+++ b/packages/playwright-core/src/client/browserType.ts
@@ -143,8 +143,8 @@ export class BrowserType extends ChannelOwner<channels.BrowserTypeChannel> imple
       connection.on('close', closePipe);
 
       let browser: Browser;
-      let closeError: Error | undefined;
-      const onPipeClosed = () => {
+      let closeError: string | undefined;
+      const onPipeClosed = (reason?: string) => {
         // Emulate all pages, contexts and the browser closing upon disconnect.
         for (const context of browser?.contexts() || []) {
           for (const page of context.pages())
@@ -152,16 +152,16 @@ export class BrowserType extends ChannelOwner<channels.BrowserTypeChannel> imple
           context._onClose();
         }
         browser?._didClose();
-        connection.close(closeError);
+        connection.close(reason || closeError);
       };
-      pipe.on('closed', onPipeClosed);
-      connection.onmessage = message => pipe.send({ message }).catch(onPipeClosed);
+      pipe.on('closed', params => onPipeClosed(params.reason));
+      connection.onmessage = message => pipe.send({ message }).catch(() => onPipeClosed());
 
       pipe.on('message', ({ message }) => {
         try {
           connection!.dispatch(message);
         } catch (e) {
-          closeError = e;
+          closeError = String(e);
           closePipe();
         }
       });
diff --git a/packages/playwright-core/src/client/connection.ts b/packages/playwright-core/src/client/connection.ts
index f468e3ff41..a5c8ef77eb 100644
--- a/packages/playwright-core/src/client/connection.ts
+++ b/packages/playwright-core/src/client/connection.ts
@@ -191,8 +191,8 @@ export class Connection extends EventEmitter {
     (object._channel as any).emit(method, validator(params, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._rawBuffers ? 'buffer' : 'fromBase64' }));
   }
 
-  close(cause?: Error) {
-    this._closedError = new TargetClosedError(cause?.toString());
+  close(cause?: string) {
+    this._closedError = new TargetClosedError(cause);
     for (const callback of this._callbacks.values())
       callback.reject(this._closedError);
     this._callbacks.clear();
diff --git a/packages/playwright-core/src/protocol/validator.ts b/packages/playwright-core/src/protocol/validator.ts
index 2a2c9d72e5..2ec820711a 100644
--- a/packages/playwright-core/src/protocol/validator.ts
+++ b/packages/playwright-core/src/protocol/validator.ts
@@ -2586,7 +2586,7 @@ scheme.JsonPipeMessageEvent = tObject({
   message: tAny,
 });
 scheme.JsonPipeClosedEvent = tObject({
-  error: tOptional(tType('SerializedError')),
+  reason: tOptional(tString),
 });
 scheme.JsonPipeSendParams = tObject({
   message: tAny,
diff --git a/packages/playwright-core/src/server/chromium/crConnection.ts b/packages/playwright-core/src/server/chromium/crConnection.ts
index ccec4663d1..c257d0d7ec 100644
--- a/packages/playwright-core/src/server/chromium/crConnection.ts
+++ b/packages/playwright-core/src/server/chromium/crConnection.ts
@@ -75,11 +75,11 @@ export class CRConnection extends EventEmitter {
       session._onMessage(message);
   }
 
-  _onClose() {
+  _onClose(reason?: string) {
     this._closed = true;
     this._transport.onmessage = undefined;
     this._transport.onclose = undefined;
-    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs());
+    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs(), reason);
     this.rootSession.dispose();
     Promise.resolve().then(() => this.emit(ConnectionEvents.Disconnected));
   }
diff --git a/packages/playwright-core/src/server/dispatchers/jsonPipeDispatcher.ts b/packages/playwright-core/src/server/dispatchers/jsonPipeDispatcher.ts
index 952e52c66f..dead26993f 100644
--- a/packages/playwright-core/src/server/dispatchers/jsonPipeDispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/jsonPipeDispatcher.ts
@@ -17,7 +17,6 @@
 import type * as channels from '@protocol/channels';
 import { Dispatcher } from './dispatcher';
 import { createGuid } from '../../utils';
-import { serializeError } from '../errors';
 import type { LocalUtilsDispatcher } from './localUtilsDispatcher';
 
 export class JsonPipeDispatcher extends Dispatcher<{ guid: string }, channels.JsonPipeChannel, LocalUtilsDispatcher> implements channels.JsonPipeChannel {
@@ -43,10 +42,9 @@ export class JsonPipeDispatcher extends Dispatcher<{ guid: string }, channels.Js
       this._dispatchEvent('message', { message });
   }
 
-  wasClosed(error?: Error): void {
+  wasClosed(reason?: string): void {
     if (!this._disposed) {
-      const params = error ? { error: serializeError(error) } : {};
-      this._dispatchEvent('closed', params);
+      this._dispatchEvent('closed', { reason });
       this._dispose();
     }
   }
diff --git a/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts b/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
index c90110a460..732e135e14 100644
--- a/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/localUtilsDispatcher.ts
@@ -230,9 +230,9 @@ export class LocalUtilsDispatcher extends Dispatcher<{ guid: string }, channels.
       pipe.on('message', message => {
         transport.send(message);
       });
-      transport.onclose = () => {
+      transport.onclose = (reason?: string) => {
         socksInterceptor?.cleanup();
-        pipe.wasClosed();
+        pipe.wasClosed(reason);
       };
       pipe.on('close', () => transport.close());
       return { pipe, headers: transport.headers };
diff --git a/packages/playwright-core/src/server/firefox/ffConnection.ts b/packages/playwright-core/src/server/firefox/ffConnection.ts
index f36dba4b23..1a24e1dbf0 100644
--- a/packages/playwright-core/src/server/firefox/ffConnection.ts
+++ b/packages/playwright-core/src/server/firefox/ffConnection.ts
@@ -77,11 +77,11 @@ export class FFConnection extends EventEmitter {
       session.dispatchMessage(message);
   }
 
-  _onClose() {
+  _onClose(reason?: string) {
     this._closed = true;
     this._transport.onmessage = undefined;
     this._transport.onclose = undefined;
-    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs());
+    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs(), reason);
     this.rootSession.dispose();
     Promise.resolve().then(() => this.emit(ConnectionEvents.Disconnected));
   }
diff --git a/packages/playwright-core/src/server/helper.ts b/packages/playwright-core/src/server/helper.ts
index 84fd0174f6..5b22dfd5e1 100644
--- a/packages/playwright-core/src/server/helper.ts
+++ b/packages/playwright-core/src/server/helper.ts
@@ -95,10 +95,10 @@ class Helper {
     };
   }
 
-  static formatBrowserLogs(logs: string[]) {
-    if (!logs.length)
+  static formatBrowserLogs(logs: string[], disconnectReason?: string) {
+    if (!disconnectReason && !logs.length)
       return '';
-    return '\n' + logs.join('\n');
+    return '\n' + (disconnectReason ? disconnectReason + '\n' : '') + logs.join('\n');
   }
 }
 
diff --git a/packages/playwright-core/src/server/pipeTransport.ts b/packages/playwright-core/src/server/pipeTransport.ts
index a84ca67023..b5755d098d 100644
--- a/packages/playwright-core/src/server/pipeTransport.ts
+++ b/packages/playwright-core/src/server/pipeTransport.ts
@@ -25,7 +25,7 @@ export class PipeTransport implements ConnectionTransport {
   private _pendingBuffers: Buffer[] = [];
   private _waitForNextTask = makeWaitForNextTask();
   private _closed = false;
-  private _onclose?: () => void;
+  private _onclose?: (reason?: string) => void;
 
   onmessage?: (message: ProtocolResponse) => void;
 
@@ -47,7 +47,7 @@ export class PipeTransport implements ConnectionTransport {
     return this._onclose;
   }
 
-  set onclose(onclose: undefined | (() => void)) {
+  set onclose(onclose: undefined | ((reason?: string) => void)) {
     this._onclose = onclose;
     if (onclose && !this._pipeRead.readable)
       onclose();
diff --git a/packages/playwright-core/src/server/transport.ts b/packages/playwright-core/src/server/transport.ts
index 6cefa270f8..e213e030e7 100644
--- a/packages/playwright-core/src/server/transport.ts
+++ b/packages/playwright-core/src/server/transport.ts
@@ -55,7 +55,7 @@ export interface ConnectionTransport {
   send(s: ProtocolRequest): void;
   close(): void;  // Note: calling close is expected to issue onclose at some point.
   onmessage?: (message: ProtocolResponse) => void,
-  onclose?: () => void,
+  onclose?: (reason?: string) => void,
 }
 
 export class WebSocketTransport implements ConnectionTransport {
@@ -64,7 +64,7 @@ export class WebSocketTransport implements ConnectionTransport {
   private _logUrl: string;
 
   onmessage?: (message: ProtocolResponse) => void;
-  onclose?: () => void;
+  onclose?: (reason?: string) => void;
   readonly wsEndpoint: string;
   readonly headers: HeadersArray = [];
 
@@ -175,7 +175,7 @@ export class WebSocketTransport implements ConnectionTransport {
     this._ws.addEventListener('close', event => {
       this._progress?.log(`<ws disconnected> ${logUrl} code=${event.code} reason=${event.reason}`);
       if (this.onclose)
-        this.onclose.call(null);
+        this.onclose.call(null, event.reason);
     });
     // Prevent Error: read ECONNRESET.
     this._ws.addEventListener('error', error => this._progress?.log(`<ws error> ${logUrl} ${error.type} ${error.message}`));
diff --git a/packages/playwright-core/src/server/webkit/wkConnection.ts b/packages/playwright-core/src/server/webkit/wkConnection.ts
index 3eb777fd73..403b32bbd6 100644
--- a/packages/playwright-core/src/server/webkit/wkConnection.ts
+++ b/packages/playwright-core/src/server/webkit/wkConnection.ts
@@ -78,11 +78,11 @@ export class WKConnection {
     this.browserSession.dispatchMessage(message);
   }
 
-  _onClose() {
+  _onClose(reason?: string) {
     this._closed = true;
     this._transport.onmessage = undefined;
     this._transport.onclose = undefined;
-    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs());
+    this._browserDisconnectedLogs = helper.formatBrowserLogs(this._browserLogsCollector.recentLogs(), reason);
     this.browserSession.dispose();
     this._onDisconnect();
   }
diff --git a/packages/protocol/src/channels.ts b/packages/protocol/src/channels.ts
index 80f88980de..a35f12791a 100644
--- a/packages/protocol/src/channels.ts
+++ b/packages/protocol/src/channels.ts
@@ -4674,7 +4674,7 @@ export type JsonPipeMessageEvent = {
   message: any,
 };
 export type JsonPipeClosedEvent = {
-  error?: SerializedError,
+  reason?: string,
 };
 export type JsonPipeSendParams = {
   message: any,
diff --git a/packages/protocol/src/protocol.yml b/packages/protocol/src/protocol.yml
index 5ac91f587f..8c9e76baef 100644
--- a/packages/protocol/src/protocol.yml
+++ b/packages/protocol/src/protocol.yml
@@ -3548,4 +3548,4 @@ JsonPipe:
 
     closed:
       parameters:
-        error: SerializedError?
+        reason: string?
diff --git a/tests/library/browsertype-connect.spec.ts b/tests/library/browsertype-connect.spec.ts
index 5dbd271264..a78814d326 100644
--- a/tests/library/browsertype-connect.spec.ts
+++ b/tests/library/browsertype-connect.spec.ts
@@ -129,6 +129,16 @@ for (const kind of ['launchServer', 'run-server'] as const) {
       expect(error.message).not.toContain('secret=MYSECRET');
     });
 
+    test('should print custom ws close error', async ({ connect, server }) => {
+      server.onceWebSocketConnection((ws, request) => {
+        ws.on('message', message => {
+          ws.close(4123, 'Oh my!');
+        });
+      });
+      const error = await connect(`ws://localhost:${server.PORT}/ws`).catch(e => e);
+      expect(error.message).toContain('browserType.connect: Oh my!');
+    });
+
     test('should be able to reconnect to a browser', async ({ connect, startRemoteServer, server }) => {
       const remoteServer = await startRemoteServer(kind);
       {
@@ -325,7 +335,7 @@ for (const kind of ['launchServer', 'run-server'] as const) {
       ]);
       expect(browser.isConnected()).toBe(false);
       const error = await page.evaluate('1 + 1').catch(e => e) as Error;
-      expect(error.message).toContain('has been closed');
+      expect(error.message).toContain('closed');
     });
 
     test('should throw when calling waitForNavigation after disconnect', async ({ connect, startRemoteServer }) => {
diff --git a/tests/library/chromium/connect-over-cdp.spec.ts b/tests/library/chromium/connect-over-cdp.spec.ts
index dd4e1c85fd..a473539e8e 100644
--- a/tests/library/chromium/connect-over-cdp.spec.ts
+++ b/tests/library/chromium/connect-over-cdp.spec.ts
@@ -527,3 +527,13 @@ test('setInputFiles should preserve lastModified timestamp', async ({ browserTyp
     await browserServer.close();
   }
 });
+
+test('should print custom ws close error', async ({ browserType, server }) => {
+  server.onceWebSocketConnection((ws, request) => {
+    ws.on('message', message => {
+      ws.close(4123, 'Oh my!');
+    });
+  });
+  const error = await browserType.connectOverCDP(`ws://localhost:${server.PORT}/ws`).catch(e => e);
+  expect(error.message).toContain(`Browser logs:\n\nOh my!\n`);
+});