Null pointer exception when calling webDriver.findElements

[ClintonMorrison]

Meta -

OS: OSX
Selenium Version: 3.3.1, IntelliJ
Browser: Chrome 60

Browser Version:
Version 60.0.3112.90 (Official Build) (64-bit)

Expected Behavior -

No null pointer exception when calling webDriver.findElements

Actual Behavior -

Occasionally, calling webDriver.findElements(By.cssSelector(query)) causes a null pointer exception. Here is the stack trace:

java.lang.NullPointerException
    at org.openqa.selenium.remote.RemoteWebDriver.findElements(RemoteWebDriver.java:450)
    at org.openqa.selenium.remote.RemoteWebDriver.findElementsByCssSelector(RemoteWebDriver.java:509)
    at org.openqa.selenium.By$ByCssSelector.findElements(By.java:441)
    at org.openqa.selenium.remote.RemoteWebDriver.findElements(RemoteWebDriver.java:402)
    at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.openqa.selenium.remote.Augmenter$CompoundHandler.intercept(Augmenter.java:189)
    at org.openqa.selenium.remote.RemoteWebDriver$$EnhancerByCGLIB$$88202d8c.findElements(<generated>)

Steps to reproduce -

It seems to happen only rarely happen so it's hard to reliably reproduce. I think it is a race condition. There was a recently a report of a similar issue in: #4375

[barancev]

Actually, it's a chromedriver issue. It must return a list of web elements (or an empty list) on this operation. But sometimes it breaks the contract and returns null. Sigh

So we have to be more defensive and convert null to an empty list on the client side. All language bindings can suffer from this issue.

[barancev]

Fixed in Java binding by 4a3ec2d

[ClintonMorrison]

Thanks @barancev!

[ClintonMorrison]

What release will this be in?

[p0deje]

Fixed in Ruby bindings in d4d8433.

[lmtierney]

Does this only affect findElements and not findChildElements?