[🐛 Bug]: Java 11 - TakeScreenshot causes exception

[martingrossmann]

Description

The getScreenshotAs method causes an AssertionError in JdkHttpMessages.readResponseBody (see #16627).

It seems to be the JDK bug https://bugs.openjdk.org/browse/JDK-8228970 which was already solved. With JDK 17 there is no issue with JDK 17.

The full stack trace is

Caused by: java.lang.AssertionError
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$HttpResponseInputStream.read(ResponseSubscribers.java:408)
	at java.base/java.io.InputStream.readNBytes(InputStream.java:396)
	at java.base/java.io.InputStream.readAllBytes(InputStream.java:333)
	at org.openqa.selenium.remote.http.jdk.JdkHttpMessages.readResponseBody(JdkHttpMessages.java:197)
	at org.openqa.selenium.remote.http.jdk.JdkHttpMessages.extractContent(JdkHttpMessages.java:190)
	at org.openqa.selenium.remote.http.jdk.JdkHttpMessages.createResponse(JdkHttpMessages.java:164)
	at org.openqa.selenium.remote.http.jdk.JdkHttpClient.execute0(JdkHttpClient.java:495)
	at org.openqa.selenium.remote.http.AddSeleniumUserAgent.lambda$apply$0(AddSeleniumUserAgent.java:44)
	at org.openqa.selenium.remote.http.Filter.lambda$andFinally$1(Filter.java:55)
	at org.openqa.selenium.remote.http.jdk.JdkHttpClient.lambda$executeAsync$2(JdkHttpClient.java:388)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

Environment

• Windows 11
• JDK 11.0.29
• Selenium 4.39
• latest Chrome

Reproducible Code

WebDriver driver = new ChromeDriver();
driver.get("https://the-internet.herokuapp.com/");
File scrFile = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);

---

ℹ️ Last known working version: 4.38

[selenium-ci]

@martingrossmann, thank you for creating this issue. We will troubleshoot it as soon as we can.

Selenium Triage Team: remember to follow the Triage Guide

[Baalaguru]

@martingrossmann I think this is not a Chrome bug or Selenium logic bug. This is a JDK 11 HTTP client bug JDK 17 fixes it

Root cause analysis & recommendation

This does not appear to be a Selenium bug, but an issue triggered by the JDK 11 java.net.http.HttpClient implementation.

The stack trace shows the failure originates from:
jdk.internal.net.http.ResponseSubscribers$HttpResponseInputStream.read
which throws an AssertionError while reading the response body. This matches the known JDK bug

JDK-8228970 (and related HTTP client stream handling issues).

• The issue reproduces on JDK 11.0.29
• The same test does not fail on JDK 17, confirming the JDK-level fix
• Selenium 4 uses the JDK HTTP client by default, which exposes this JDK bug
• Selenium is correctly consuming the HTTP response
• The AssertionError originates from the JDK HTTP client
• This is fixed in newer JDKs (17+)

[martingrossmann]

Hi @Baalaguru, thank you for your response.

This is what I already assumed. Therefor, Selenium 4.39 cannot used any more with JDK 11. The minimum required version is JDK 17.

[titusfortner]

But it worked with 4.38 and isn't working in 4.39?
Was there something we changed in 4.39 that caused this?

[cgoldberg]

it worked with 4.38 and isn't working in 4.39?
Was there something we changed in 4.39 that caused this?

It looks like it is caused by this line:

https://github.com/asolntsev/selenium/blob/875f5f551ff10907ccd5e877b042d554603e122f/java/src/org/openqa/selenium/remote/http/jdk/JdkHttpMessages.java#L197

It comes from #16627 that was introduced in 4.39.

The linked JDK bug shows you get an AssertionError in Java 11 if you try to read an empty InputStream.

I think we can work around it by catching AssertionError and either returning an empty byte array or throwing UncheckedIOException if that is handled somewhere else.

[cgoldberg]

@asolntsev Can you look into this? It would be nice to add a workaround for Java 11