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Use the .NET integration pattern first
Puppeteer-sharp-extra provides the .NET plugin wrapper, while PuppeteerSharp supplies browser automation. The documented setup creates a PuppeteerExtra instance, registers StealthPlugin, and launches through that wrapper.
Minimal C# example
using PuppeteerExtraSharp;
using PuppeteerExtraSharp.Plugins.Stealth;
var extra = new PuppeteerExtra();
extra.Use(new StealthPlugin());
await using var browser = await extra.LaunchAsync();
await using var page = await browser.NewPageAsync();
await page.GoToAsync("https://example.com");
Console.WriteLine(await page.GetTitleAsync());The exact namespaces can vary with the package version, so let your IDE resolve them from the installed assembly. If PuppeteerExtra or StealthPlugin cannot be found, the project probably has PuppeteerSharp alone, the wrong package, or a package version whose API differs from the example.
Separate Node.js code from C# code
The upstream JavaScript project documents a pattern similar to puppeteer.use(StealthPlugin()). That syntax belongs to the Node packages puppeteer-extra and puppeteer-extra-plugin-stealth, described in the upstream stealth README. It is not a C# API.
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- Node.js: JavaScript packages,
requireorimport, andpuppeteer.use(...). - .NET: NuGet packages, C# namespaces,
PuppeteerExtra,Use(new StealthPlugin()), andLaunchAsync().
Remove JavaScript imports from a .NET project and verify that your project references PuppeteerExtraSharp, not only PuppeteerSharp.
Check the packages that are actually resolved
A project file can contain a version range while NuGet resolves a different version through a transitive dependency. Inspect the resolved graph and compare the two libraries before debugging a method call.
Commands
dotnet list package
dotnet list package --include-transitiveRecord the resolved versions of PuppeteerSharp and PuppeteerExtraSharp. Also record your target framework from the <TargetFramework> element in the project file. Compare those versions with the compatibility information in the package listing and the source repository. A clean rebuild after changing versions prevents stale binaries from hiding the result:
dotnet clean
dotnet restore
dotnet buildDo not assume that the newest release of one package is compatible with every release of the other. Align versions supported by the package documentation, then retest the smallest possible program.
Identify where the error occurs
| Symptom stage | Typical signal | What to inspect first |
|---|---|---|
| Build or compile | Type, namespace, method, or overload does not exist | Package identity, resolved versions, namespace, and API signature |
| Browser launch | Exception while calling LaunchAsync |
Launch options, browser executable/download, and compatible package versions |
| Navigation | Page timeout, challenge, CAPTCHA, or access denial | Target-site behavior, network conditions, and whether automation is being blocked |
A site refusing navigation is not proof that the plugin failed to load. Conversely, a missing method at compile time cannot be fixed by changing user-agent or stealth settings.
Resolve missing-method and overload errors carefully
One secondary troubleshooting report mentions a mismatch between EvaluateExpressionOnNewDocumentAsync(string) and EvaluateFunctionOnNewDocumentAsync(string). Treat this as a diagnostic lead, not a universal patch. The correct method depends on the PuppeteerSharp version, the plugin version, and whether the supplied script is an expression or a function.
- Copy the complete error, including the assembly and method signature named by the compiler or runtime.
- Open the API reference for the same PuppeteerSharp version. The general references are the PuppeteerSharp API and LaunchOptions API; do not use documentation for a different release.
- Check the plugin source or package version for the exact call that fails.
- Confirm the expected script format before changing the method. A function-oriented API and an expression-oriented API are not interchangeable merely because both accept a string.
- Rebuild with the aligned package set and test a minimal page.
If the plugin internally calls a method absent from your resolved PuppeteerSharp assembly, upgrading or downgrading only one package can make the mismatch worse. Change the pair deliberately and keep the versions recorded for reproducibility.
Use launch options only after integration works
Once the wrapper compiles, add launch settings incrementally. Start with the default launch, then introduce one option at a time so an invalid executable path, argument, or headless setting is not mistaken for a StealthPlugin problem.
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var extra = new PuppeteerExtra();
extra.Use(new StealthPlugin());
var browser = await extra.LaunchAsync(new PuppeteerSharp.LaunchOptions
{
Headless = true
});Consult the version-matched LaunchOptions documentation for available properties. Browser download and executable requirements can differ by PuppeteerSharp release, operating system, and deployment environment; capture the full launch exception rather than replacing options randomly.
When the target site still blocks you
The stealth project’s stated purpose is to make headless automation harder to detect. It does not guarantee that a target accepts automation. A successful build and browser launch can therefore be followed by a CAPTCHA, challenge page, HTTP denial, or application-level block.
- Save the final URL and response or page title.
- Check whether a normal interactive browser reaches the same page from the same network.
- Separate a timeout or failed load from an explicit bot challenge.
- Respect the site’s terms, robots policy, authentication rules, and applicable law.
- Do not treat stealth as a way to defeat access controls.
These symptoms require application and site-behavior diagnosis, not a blind substitution of evaluation methods.
Build a minimal reproducible test
Reduce the project to one target framework, the two relevant NuGet packages, and one navigation. Remove proxies, custom scripts, parallel pages, and unrelated middleware. Then capture:
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- Operating system and .NET SDK version.
- Target framework.
- Resolved PuppeteerSharp and PuppeteerExtraSharp versions from
dotnet list package --include-transitive. - Complete compiler or exception text, including inner exceptions.
- The smallest code sample that reproduces the failure.
- The stage: build, launch, page creation, navigation, or post-navigation evaluation.
This information lets maintainers distinguish a missing reference from a version mismatch and a package exception from a target-site response.
Common errors and targeted fixes
“The type or namespace name PuppeteerExtraSharp could not be found”
Cause: the .NET wrapper is not installed or restore failed. Fix: add the PuppeteerExtraSharp package, run restore, and verify the resolved package list. Ensure the project is not accidentally referencing only JavaScript packages.
“StealthPlugin could not be found”
Cause: missing plugin namespace, wrong package version, or an incomplete package set. Fix: inspect the package’s documented namespaces for your version and let the IDE import the type from the referenced assembly.
“Method … does not exist”
Cause: API drift or incompatible PuppeteerSharp/PuppeteerExtraSharp versions. Fix: compare the exact signature with the matching API reference and plugin source. Investigate the expression-versus-function method report only after this check.
Launch fails before a page opens
Cause: browser executable, download, permissions, or launch-option problems. Fix: run the wrapper with default options, verify the browser installation expected by your PuppeteerSharp release, and then add options one at a time.
Navigation reaches a CAPTCHA or denial page
Cause: target-site detection or access policy, not necessarily plugin integration. Fix: log the final URL and page content, test a permitted page, and handle the block as a site-access issue.
Reliability and maintenance practices
- Pin known-compatible package versions instead of floating ranges in production.
- Check transitive dependencies after every upgrade.
- Keep a startup health check that launches a browser and opens a harmless test URL.
- Log package versions, target framework, launch stage, and inner exceptions without exposing credentials.
- Use bounded navigation and operation timeouts so a failed site cannot hang a worker indefinitely.
- Retest after browser, .NET SDK, or operating-system upgrades.
Stealth evasions can change upstream, and sites can change their detection systems. Treat the plugin as one component in a monitored automation system, not as a permanent compatibility guarantee.
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Frequently Asked Questions
Can I use the Node.js stealth package directly from C#?
No. Use the .NET PuppeteerExtraSharp wrapper and its C# API; the Node package syntax is for a separate JavaScript runtime and package set.
Is changing EvaluateExpressionOnNewDocumentAsync enough to fix every error?
No. That substitution is only a reported lead. Verify the method, script type, and compatible package versions for your installation.
Does StealthPlugin guarantee that a site will not detect automation?
No. It makes automation harder to detect, but target sites can still challenge or block automated browsing.
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