org.openqa.selenium.WebDriverException: Session [null] not available and is not among the last 1000 terminated sessions using SeleniumGrid in Docker

Question

I am running selenium grid and has 2 nodes connected to it. But when I try to run a test script (.java) it gives the error:

Exception in thread "Thread-23" org.openqa.selenium.WebDriverException: Session [null] not available and is not among the last 1000 terminated sessions.
Active sessions are[ext. key 3e5f8fb2ae3b0c5cddc8817f80eb8fe1]
Command duration or timeout: 92 milliseconds
Build info: version: 'unknown', revision: 'unknown', time: 'unknown'

In the VNC client the chrome browser opens up but the url is not getting loaded and the error is thrown.

Note: The script is run from another docker container using maven.

When I run the script as a java application, it works fine, but in docker, I'm getting the error.**

Answer 1

This error message...

Exception in thread "Thread-23" org.openqa.selenium.WebDriverException: Session [null] not available and is not among the last 1000 terminated sessions.
Active sessions are[ext. key 3e5f8fb2ae3b0c5cddc8817f80eb8fe1]
Command duration or timeout: 92 milliseconds
Build info: version: 'unknown', revision: 'unknown', time: 'unknown'

...implies that the Selenium Grid Node was unable to communicate with the Selenium Grid Hub.

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Deep Dive

This error is defined in ActiveTestSessions.java and is defined as:

public TestSession getExistingSession(ExternalSessionKey externalkey) {
    TestSession sessionByExternalKey = findSessionByExternalKey(externalkey);
    if (sessionByExternalKey == null) {
      SessionTerminationReason sessionTerminationReason = reasons.get(externalkey);
      String keyId = externalkey != null ? externalkey.getKey() : "(null externalkey)";
      if (sessionTerminationReason != null) {
          String msg = "Session [" + keyId + "] was terminated due to " + sessionTerminationReason;
          log.fine(msg);
          throw new GridException(msg);
      } else {
          String msg = "Session [" + keyId + "] not available and is not among the last 1000 terminated sessions.\n"
          + "Active sessions are" + this.unmodifiableSet();
          log.fine(msg);
          throw new GridException(msg);
      }
    }
    return sessionByExternalKey;
}

As per the following discussions:

• Session [....] not available and is not among the last 1000 terminated sessions
• Selenium 3.9.0 & above gives error "Session [null] not available and is not among the last 1000 terminated sessions." on geckodriver

It seems this error stems out when:

• Selenium Grid Hub, Selenium Grid Node and the Client Process are initiated/spawned from different versions of Selenium client.

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Solution

Ensure that Selenium Grid Hub, Selenium Grid Node and the Client Process all of them uses the same version of Selenium client i.e. Selenium v3.141.59

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Update 1

In normal circumstances you should have observed Selenium Webdriver + Java - Eclipse: java.lang.NoClassDefFoundError incase of presence of multiple versions of the same jar. A bit more details interms of your Test Architecture would have helped us to debug the issue in a better way. Possibly you need to clean up as follows:

• mvn clean
• mvn install
• or mvn clean install
• mvn test

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Update 2

As the last resort you can delete the MAVEN_HOME i.e. ~/.m2 and re-initiate the build process.