[🐛 Bug]: No connection could be made because the target machine actively refused it.

[Pandzioch]

What happened?

Hi dear developers.

So what I currently struggle with is a problem with C# Selenium with SocketException for ChromeDriver:

[09:30:07 ]   OpenQA.Selenium.WebDriverException : An unknown exception was encountered sending an HTTP request to the remote WebDriver server for URL http://localhost:23391/session/9e1b9a2ff8740b399050adc85714d15d/element. The exception message was: No connection could be made because the target machine actively refused it. (localhost:23391)
09:30:07     ----> System.Net.Http.HttpRequestException : No connection could be made because the target machine actively refused it. (localhost:23391)
[09:30:07 ]   ----> System.Net.Sockets.SocketException : No connection could be made because the target machine actively refused it.

I've done some digging into this to actually find what's wrong.
Setup of the test is pretty straightforward, driver is being initialized with ChromeOptions:
"--start-maximized",
"--no-sandbox",
"--proxy-server='direct://'",
"--proxy-bypass-list=*",
This error occurs not only on CI/CD but my local machine also, what's worth mentioning is that for 60+ automated test cases, the error comes usually once per run.

Configuration setup looks like this:

• ChromeDriver is being run from the package Selenium.WebDriver.ChromeDriver 113.0.5672.6300
• Test are runnig by local chromedriver -> local test, no grid, docker, or cloud is being used.
• CI/CD are running by the TeamCity agent, tests are being invoked by the usage of CommandLine with the command "dotnet test"
• All packages are up to date
• Chrome is up to date 113.0.5672.127 (64-bit)
• .NET SDK 5.0.408
• No proxy is set on the machine, on the server or the ChromeOptions
• No VPN is set on any of the machines

I've tried all the solutions I could find by searching all across the internet by found no good.
What's even funnier, the downgrade from .NET 6.0 to .NET 5.0 project reduced this error by a lot (From 3-4 crashes to 1 or none)

How can we reproduce the issue?

I cannot share the source code of my repo due to the fact that it's unallowed by my contract but I'll try to do my best to describe it.

Crash of the webdriver happens mostly at random. There's no part of the code which triggers it at the same place currently. For example, if test consists of 20 steps to do, it can fail at 1 step, 15, or even the last one.

But what I think a hint may be is one NuGet Package & few methods used.
- I'm using DotNetSeleniumExtras.WaitHelpers package in ver 3.11.0 which catches most of the time StaleElementReference exceptions, one test was waiting for an angular overlay to drop with method ExpectedConditions.InvisibilityOfElementLocated which was crashing quite often, deleting it and using Thread.Sleep(XAmmountOfTime) solved the problem.
Same thing goes for the method ExpectedConditions.UrlContains("some string of an url")
- The method that also crashes from time to time is driver.Navigate().GoToUrl("some url")

The more tests are there, the higher chance of the error to occur

Relevant log output

09:30:07     Error Message:
09:30:07      OpenQA.Selenium.WebDriverException : An unknown exception was encountered sending an HTTP request to the remote WebDriver server for URL http://localhost:23391/session/9e1b9a2ff8740b399050adc85714d15d/element. The exception message was: No connection could be made because the target machine actively refused it. (localhost:23391)
09:30:07     ----> System.Net.Http.HttpRequestException : No connection could be made because the target machine actively refused it. (localhost:23391)
09:30:07     ----> System.Net.Sockets.SocketException : No connection could be made because the target machine actively refused it.
09:30:07   TearDown : OpenQA.Selenium.WebDriverException : An unknown exception was encountered sending an HTTP request to the remote WebDriver server for URL http://localhost:23391/session/9e1b9a2ff8740b399050adc85714d15d/screenshot. The exception message was: No connection could be made because the target machine actively refused it. (localhost:23391)
09:30:07     ----> System.Net.Http.HttpRequestException : No connection could be made because the target machine actively refused it. (localhost:23391)
09:30:07     ----> System.Net.Sockets.SocketException : No connection could be made because the target machine actively refused it.
09:30:07     Stack Trace:
09:30:07        at OpenQA.Selenium.Remote.HttpCommandExecutor.Execute(Command commandToExecute)
09:30:07      at OpenQA.Selenium.Remote.DriverServiceCommandExecutor.Execute(Command commandToExecute)
09:30:07      at OpenQA.Selenium.WebDriver.Execute(String driverCommandToExecute, Dictionary`2 parameters)
09:30:07      at OpenQA.Selenium.WebDriver.FindElement(String mechanism, String value)
09:30:07      at OpenQA.Selenium.By.<.ctor>b__11_0(ISearchContext context)
09:30:07      at OpenQA.Selenium.By.FindElement(ISearchContext context)
09:30:07      at OpenQA.Selenium.WebDriver.FindElement(By by)
09:30:07      at SeleniumExtras.WaitHelpers.ExpectedConditions.<>c__DisplayClass17_0.<InvisibilityOfElementLocated>b__0(IWebDriver driver)
09:30:07      at OpenQA.Selenium.Support.UI.DefaultWait`1.Until[TResult](Func`2 condition, CancellationToken token)
09:30:07      at OpenQA.Selenium.Support.UI.DefaultWait`1.Until[TResult](Func`2 condition)
09:30:07      at Eagle.Framework.Models.E2E.Wait.Until(Func`2 condition) in C:\BuildAgent\work\d20cd7016e022376\Eagle.Framework\Models\E2E\Wait.cs:line 30
09:30:07      at Eagle.Framework.PageObjects.mCalendar.mCalendar.SaveConference() in C:\BuildAgent\work\d20cd7016e022376\Eagle.Framework\PageObjects\mCalendar\mCalendar.cs:line 303
09:30:07      at Eagle.E2E.Test.StepDefinitions.mCalendarStepDefinitions.ThenKonferencjaZostajeZapisana() in C:\BuildAgent\work\d20cd7016e022376\Eagle.E2E.Test\StepDefinitions\mCalendarStepDefinitions.cs:line 302
09:30:07      at TechTalk.SpecFlow.Bindings.BindingInvoker.InvokeBinding(IBinding binding, IContextManager contextManager, Object[] arguments, ITestTracer testTracer, TimeSpan& duration)
09:30:07      at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.ExecuteStepMatch(BindingMatch match, Object[] arguments, TimeSpan& duration)
09:30:07      at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.ExecuteStep(IContextManager contextManager, StepInstance stepInstance)
09:30:07      at TechTalk.SpecFlow.Infrastructure.TestExecutionEngine.OnAfterLastStep()
09:30:07      at TechTalk.SpecFlow.TestRunner.CollectScenarioErrors()
09:30:07      at Eagle.E2E.Test.Features.MKalendarz_KonferencjeFeature.ScenarioCleanup()
09:30:07      at Eagle.E2E.Test.Features.MKalendarz_KonferencjeFeature.Sale_Edycja() in C:\BuildAgent\work\d20cd7016e022376\Eagle.E2E.Test\Features\mCalendarConferences.feature:line 178
09:30:07   --HttpRequestException

Operating System

Windows 10, Windows Server 2016 Standard

Selenium version

C# Selenium.WebDriver 4.9.1, NUnit 3.13.3, NUnit3TestAdapter 4.4.2

What are the browser(s) and version(s) where you see this issue?

GoogleChrome 113.0.5672.127 (64-bit)

What are the browser driver(s) and version(s) where you see this issue?

Selenium.WebDriver.ChromeDriver 113.0.5672.6300

Are you using Selenium Grid?

No

[github-actions]

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

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Thank you!

[titusfortner]

Why are you setting these if there is no proxy on the machine?

"--proxy-server='direct://'",
"--proxy-bypass-list=*",

The only supported means in Selenium to pass proxy information is with the Proxy property in the options class.

Further, DotNetSeleniumExtras is explicitly unmaintained an unsupported, so if you think that is causing a problem, the recommendation is to create your own anonymous functions.

Finally, in order to consider this issue a bug, we need a minimal reproducible example

[github-actions]

Hi, @Pandzioch.
Please follow the issue template, we need more information to reproduce the issue.

Either a complete code snippet and URL/HTML (if more than one file is needed, provide a GitHub repo and instructions to run the code), the specific versions used, or a more detailed description to help us understand the issue.

Note: If you cannot share your code and URL/HTML, any complete code snippet and URL/HTML that reproduces the issue is good enough.

Reply to this issue when all information is provided, thank you.

[Pandzioch]

@titusfortner
"--proxy-server='direct://'", "--proxy-bypass-list=*",
Those options were set as a part of terminal "Solution" in the meanwhile as I was verifying the proxy setup for machines. It's now removed (It didn't change behavior in any way).

I took my time to work with those waiting methods and removed DotNetSeleniumExtras NuGet (this also goes for SeleniumExtras.WaitHelpers).
^
And that's actually a solution to this problem. I really don't know why, because it was only checking the IWebElement status and capturing NoSuchElement & Staleness Exceptions but the error description is pointing to:
System.Net.Sockets.SocketException : No connection could be made because the target machine actively refused it.
So either the Driver got busy or stuck itself on something.

I wish I could give You a straight copy-paste of the code, but as I've mentioned before that cannot be done.
Will try to reproduce it on my private machine to clarify the process.

[titusfortner]

So moving to anonymous functions fixed your problem?

If you don't still have an problem, I wouldn't spend time trying to figure out why you had it. We can close this issue and have another example of why people should avoid expected conditions classes.

[Pandzioch]

Well, it didn't solve my problem per se.
This method below makes the problem

[titusfortner]

So that method sometimes throws a socket exception.... I can't remember if that error is essentially a kind of timeout.

Are you running multiple tests in parallel? Is the system under test overtaxed?

[Pandzioch]

Tests are running as nonparallel due to the usage of SpecFlow as a BDD overlay. At the moment of the run, I was the only person using it at the time.

I've changed the method for invisibility of the element to:

       public static Func<IWebDriver, bool> InvisibilityOf(By locator) => delegate (IWebDriver driver)
        {
            return driver.FindElements(locator).Count == 0;
        };

Which seems to be working fine (at least for now). But I kinda don't understand the message here because:
The exception message was: No connection could be made because the target machine actively refused it.
It seems like a network issue, rather than a timeout. Maybe You have some more insight into this kind of an exception

[titusfortner]

Yeah, this seems like some kind of network issue. The question is whether it is immediately throwing the error or if there is some time it is waiting and then throwing the error. If there is a time difference, is the problem that the difference isn't enough time given, or would it always fail, regardless. I'm not sure how to debug this one more.

[Pandzioch]

Based on my personal experience, for most of the runs, the issue occurred on a slight timeout, around 3-4 seconds. It looks like waiting and then throwing an error.
I found one case in which the test got stuck for about an hour (teamcity agent closed the run due to the timeout settings) in this method.
From my approach, we can close this thread, because well, it's even hard to pull off without giving a set of as many automated tests possible with the usage of that particular library. Maybe there should be a prevention mechanism for this, I really don't know.

Anyway, I really appreciate Your time Titus, thanks for looking at it.
Maybe selenium documentation page should have like one big red banner with "Don't use nuget packages with waits" 😆

[titusfortner]

We're going to be talking more about this going forward. I'm hoping for Selenium 5 to take the approach that .NET did and move some of these helper libraries outside of Selenium proper for all the languages.