[🐛 Bug]: [java] Remote file download fails with "Don't serialize binary stream - it might be large" using RemoteWebDriver.builder()

[tim-burke-systemware]

Description

Environment

• Selenium: 4.40.0
• OS: Windows 11 x64
• Java: 21.0.10
• Selenium client: Using RemoteWebDriver.builder()
• Logging: org.openqa.selenium set to FINER

---

Description

When attempting to download a file with .downloadFile() from a Grid node using RemoteWebDriver.builder() (the "new" builder-style API), the command fails with:

org.openqa.selenium.WebDriverException: Don't serialize binary stream - it might be large

This is due to the inclusion of DumpHttpExchangeFilter in the RemoteWebDriver.builder()'s client filter chain, which logs all HTTP exchanges. When downstream code tries to log a streamed file download response, it calls contentAsString() on the binary stream, which triggers this error.

This does not occur when:

• Using the legacy new RemoteWebDriver(URL, Capabilities) constructor

How to Reproduce

1. Set up Selenium Grid (standalone is enough), enable se:downloads.
2. Set logging for org.openqa.selenium to FINER or higher.
3. Run reproducible code

Suspected Root Cause

• DumpHttpExchangeFilter logs HTTP responses by calling Contents.string(HttpMessage), which invokes .contentAsString() on the response object.
• If the response is a streamed binary (InputStreamContentSupplier), this throws UnsupportedOperationException("Don't serialize binary stream - it might be large").
• The filter chain includes ErrorFilter, which swallows the exception and turns it into a 500 error, which is thrown by the response codec as a WebDriverException to the caller.

Code/Reference Links

• DumpHttpExchangeFilter.java
• ErrorFilter.java
• RemoteWebDriverBuilder.java
• Relevant filter chain setup

Reproducible Code

import org.openqa.selenium.chrome.ChromeOptions;
import org.openqa.selenium.remote.RemoteWebDriver;
import java.net.URL;
import java.nio.file.Paths;

RemoteWebDriver driver = RemoteWebDriver.builder()
    .address(new URL("http://localhost:4444/"))
    .addAlternative(new ChromeOptions()) // or your browser options
    .build();

driver.get("https://the-internet.herokuapp.com/download/Coffee.pptx");
driver.downloadFile("Coffee.pptx", Paths.get("."));
driver.quit();

Debugging Logs

Build info: version: '4.40.0', revision: 'b3333f1'
System info: os.name: 'Windows 11', os.arch: 'amd64', os.version: '10.0', java.version: '21.0.10'
Driver info: org.openqa.selenium.remote.RemoteWebDriver$ByteBuddy$a6W6ipHt$ByteBuddy$TTVVMAQ4
Command: [57d2b9aba360662c6a7005bfcbfd4841, downloadFile {format=application/octet-stream, name=modifiedcamfiles.zip}]
Capabilities {acceptInsecureCerts: true, browserName: chrome, browserVersion: 145.0.7632.117, chrome: {chromedriverVersion: 145.0.7632.117 (de4e5d6e13b..., userDataDir: C:\Users\DEV~1.SER\AppData\...}, fedcm:accounts: true, goog:chromeOptions: {debuggerAddress: localhost:58556}, goog:loggingPrefs: {browser: ALL, driver: ALL}, goog:processID: 776, networkConnectionEnabled: false, pageLoadStrategy: normal, platformName: Windows XP, proxy: Proxy(), se:bidiEnabled: false, se:cdp: wss://192.168.20.108:4444/s..., se:cdpVersion: 145.0.7632.117, se:downloadsEnabled: true, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: dismiss and notify, webauthn:extension:credBlob: true, webauthn:extension:largeBlob: true, webauthn:extension:minPinLength: true, webauthn:extension:prf: true, webauthn:virtualAuthenticators: true}
Session ID: 57d2b9aba360662c6a7005bfcbfd4841
	at org.openqa.selenium.remote.ErrorCodec.decode(ErrorCodec.java:169)
	at org.openqa.selenium.remote.codec.w3c.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:142)
	at org.openqa.selenium.remote.codec.w3c.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:49)
	at java.base/java.util.function.Function.lambda$andThen$1(Function.java:88)
	at org.openqa.selenium.remote.RemoteWebDriverBuilder.lambda$createExecutor$9(RemoteWebDriverBuilder.java:483)
	at org.openqa.selenium.remote.RemoteWebDriverBuilder.lambda$createExecutor$10(RemoteWebDriverBuilder.java:490)
	at org.openqa.selenium.remote.RemoteWebDriverBuilder.lambda$createExecutor$11(RemoteWebDriverBuilder.java:495)
	at org.openqa.selenium.remote.RemoteWebDriverBuilder.lambda$createExecutor$12(RemoteWebDriverBuilder.java:505)
	at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:601)
	at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:678)
	at org.openqa.selenium.remote.RemoteWebDriver.downloadFile(RemoteWebDriver.java:774)
	at com.systemware.swuitests.components.BaseComponent.getDownload(BaseComponent.java:2297)

[selenium-ci]

@tim-burke-systemware, thank you for creating this issue. We will troubleshoot it as soon as we can.

Selenium Triage Team: remember to follow the Triage Guide

[github-actions]

⚠️ You reported using Selenium version 4.40, but the latest release is 4.41.

Please verify that this issue still occurs with the latest version. If it no longer applies, you can close this issue or update your comment.

This issue will be marked "awaiting answer" and may be closed automatically if no response is received.

[tim-burke-systemware]

⚠️ You reported using Selenium version 4.40, but the latest release is 4.41.

Please verify that this issue still occurs with the latest version. If it no longer applies, you can close this issue or update your comment.

This issue will be marked "awaiting answer" and may be closed automatically if no response is received.

Issue is still present for 4.41