WebDriverException: Returned value cannot be converted to WebElement: {} while using WebDriver with Safari 11 on Mac OS X

问题

I have a selenium webdriver script which performs some regression tests on my application under test. The script works perfectly on Google Chrome, Firefox, IE, etc.

However, recently I tried running it on Safari (11.1.1) on Mac OS X (10.13.5), and my script fails with a weird message even when I call a simple line such as

driver.findElement(By.tagName("body"));

The exception I get is as follows:

org.openqa.selenium.WebDriverException: Returned value cannot be converted to WebElement: {}
Build info: version: '3.0.1', revision: '1969d75', time: '2016-10-18 09:49:13 -0700'
System info: host: 'Yethis-MacBook-Pro.local', ip: '192.168.2.197', os.name: 'Mac OS X', os.arch: 'x86_64', os.version: '10.13.5', java.version: '1.8.0_171'
Driver info: driver.version: RemoteWebDriver
    at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:375)
    at org.openqa.selenium.remote.RemoteWebDriver.findElementByTagName(RemoteWebDriver.java:441)
    at org.openqa.selenium.By$ByTagName.findElement(By.java:334)
    at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:360)
    at org.ycs.selenium.safari.App.execute(App.java:75)
    at org.ycs.selenium.safari.App.main(App.java:27)
Caused by: java.lang.ClassCastException: com.google.common.collect.Maps$TransformedEntriesMap cannot be cast to org.openqa.selenium.WebElement
    at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:373)
    ... 5 more

Selenium Version: 3.0.1 Safari Version: 11.1.1 Java Version: 1.8 OS X version: 10.13.5

Edit: This is my dependency configured in maven

<dependency>
    <groupId>org.seleniumhq.selenium</groupId>
    <artifactId>selenium-server</artifactId>
    <version>3.0.1</version>
</dependency>

I tried doing a lot of search for this issue, but unfortunately, nothing showed up with Mac specific information.

Could anyone help me solve this problem please?

Thanks, Sriram Sridharan

回答1:

This error message...

org.openqa.selenium.WebDriverException: Returned value cannot be converted to WebElement: {}

...implies that WebDriverException was raised while JVM tried to cast the returned value into a WebElement.

However your main issue is as follows:

java.lang.ClassCastException: com.google.common.collect.Maps$TransformedEntriesMap cannot be cast to org.openqa.selenium.WebElement

ClassCastException

ClassCastException is thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. As an example, the following code generates a ClassCastException:

Object x = new Integer(0);
System.out.println((String)x);

What went wrong

It is not clear about your usecase why you require to grab the <body> tag. But as per the following discussions:

java.lang.ClassCastException exception while clicking/inputing on any web object
WebDriver and Firefox 4+: this.getWindow() is null

There can be three possibilities of this error as follows:

Your script/program was trying to access the <body> tag when the page was still loading perhaps when some JavaScript / Ajax was still active.

Solution: Induce WebDriverWait for the WebElement to whom you desire to interact with as follows:

WebElement element = new WebDriverWait(driver, 20).until(ExpectedConditions.elementToBeClickable(By.id("elementID")));

If you want to get the Page Source use getPageSource() method as follows:
```
System.out.println(driver.getPageSource());
```
If the control of the program was within an <iframe> before trying to find the <body> tag, switch back to the defaultContent as follows:
```
driver.switchTo().defaultContent();
```

Note: As per best practices always keep your Test Environment updated with the latest releases.

Update the Selenium Client dependency to 3.12.0:

selenium-java:

<dependency>
    <groupId>org.seleniumhq.selenium</groupId>
    <artifactId>selenium-java</artifactId>
    <version>3.12.0</version>
</dependency>

selenium-server:

<dependency>
    <groupId>org.seleniumhq.selenium</groupId>
    <artifactId>selenium-server</artifactId>
    <version>3.12.0</version>
</dependency>

来源：https://stackoverflow.com/questions/51020225/webdriverexception-returned-value-cannot-be-converted-to-webelement-while-u

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java

macos

selenium

selenium-webdriver

safari