Web Scraping & API Glossary

When you call browser.newPage() on a browser connected via connectOverCDP(), Playwright throws "Cannot read properties o...

Playwright's getByRole() locator uses the browser's accessibility tree to find elements by their semantic role. When you...

This error means a JavaScript evaluation—like page.evaluate() or page.evaluateHandle()—was interrupted because the page ...

The message "execution context was destroyed, most likely because of a navigation" means Playwright started evaluating J...

"Frame was detached" means the iframe you were interacting with was removed from the DOM or replaced while your script h...

page.goto: net::ERRABORTED means the browser started a navigation but the request was cancelled before a response was re...

net::ERRCONNECTIONREFUSED means the browser attempted a TCP connection to the target host and port, and the operating sy...

net::ERRINTERNETDISCONNECTED means the browser has no active network path to reach the target — either the machine itsel...

net::ERRINVALIDAUTH_CREDENTIALS is thrown when a server challenges the browser with HTTP Basic Authentication and the cr...

When Playwright's request fixture (or APIRequestContext) is used alongside page in the same test, their cookies and sess...

This happens when the authentication setup step saves session state to a file, but the test project that runs your tests...

Exact text assertions break on whitespace normalization, added punctuation, translated strings, or copy edits that don't...

Clicking a button that is disabled or in a loading state produces no action — the click goes through Playwright's action...

Cannot read properties of undefined in a Playwright test is a JavaScript runtime error, not a browser or network error. ...

npx playwright install --with-deps chromium fails on Ubuntu 26.04 with something like Unsupported platform: ubuntu26.04-...

Playwright browser launches fail in CI when the container image is missing the Linux shared libraries that Chromium requ...

This timeout fires when the element exists in the DOM but Playwright cannot confirm it is visible, enabled, and not obsc...

CSS class selectors in Playwright tests couple test code to implementation details of the component's styling. When a de...

This error means a test() call was executed outside of a spec file — most commonly because a helper module or config fil...

Download tests hang when the event listener is attached after the download has already started. The browser fires the do...

"Element is not attached to the DOM" surfaces when a Playwright action targets an element that was in the DOM when queri...

net::ERRNAMENOT_RESOLVED means the browser's DNS resolver could not find an IP address for the hostname in the URL. In P...

The "Executable doesn't exist" error means the @playwright/test package is installed but the corresponding browser binar...

"Execution context was destroyed" appears when Playwright has a JavaScript handle or evaluation in flight and the page n...

File upload failures in Playwright almost always come down to three root causes: targeting the wrong element (a styled <...

Geolocation and browser permissions fail to apply in Playwright tests when they are set at the wrong stage of the browse...

Headless-only failures are among the most confusing Playwright issues because the test is syntactically correct and pass...

Playwright on Windows fails to launch headlessshell.exe with an error about missing DLL files — often vcruntime140.dll, ...

Playwright's role-based locators (getByRole, getByLabel) match elements using the computed accessible name, which may co...

locator.isVisible() is a point-in-time query that returns the current visibility state immediately without any retrying....

Leaked state between tests happens when one test leaves side effects that affect subsequent tests in the same worker: co...

locator.count() returns a number immediately — it does not assert, does not retry, and does not fail if the count is wro...

Mobile emulation in Playwright fails to trigger the mobile layout when viewport and device settings are applied after co...

networkidle as a waitUntil condition tells Playwright to wait until there are no network connections for at least 500ms....

"No frame for selector" and similar iframe-related errors happen when test code tries to locate elements inside an ifram...

Index-based locators with .nth() are fragile because they rely on the DOM rendering elements in a specific, stable order...

getByText() matches any element in the document that contains the specified text, including headings, list items, table ...

page.waitForTimeout() (a hard sleep) is the most common anti-pattern in Playwright test suites. It introduces fixed dela...

Parallel Playwright workers interact with a shared database simultaneously, causing data collisions when tests assume ex...

Popup and new-tab tests become flaky when page.waitForEvent('popup') is called after the action that opens the popup. Ju...

A "Protocol error: invalid argument" originates from the Chrome DevTools Protocol (CDP) layer and means Playwright sent ...

Random browser crashes in CI — where tests pass locally but fail unpredictably in CI runners — are almost always resourc...

Playwright retries are designed to improve stability for genuinely intermittent conditions — network latency, slow CI ma...

Route mocking fails silently when the URL pattern doesn't match what the browser actually requests, or when page.route()...

Shadow DOM components encapsulate their internal DOM in a shadow root that is intentionally hidden from the main documen...

Playwright's --shard=N/M splits test files across M runners, but the distribution is based on file count — not test coun...

A strict mode violation in Playwright fires when a locator resolves to more than one element at action time. The error m...

When this error appears alongside a crash — rather than an orderly context.close() call — it means the browser process e...

TimeoutError is thrown when Playwright cannot complete an action or find an actionable element within the configured tim...

waitForResponse misses requests for exactly the same reason waitForEvent('download') and waitForEvent('popup') do — the ...

Weak URL assertions allow tests to pass on the wrong page, producing false positives that hide navigation bugs. expect(p...

Tests that depend on WebSocket connections or Server-Sent Events (SSE) are inherently more sensitive to CI network insta...

Memory-related worker crashes in Playwright parallel runs manifest as browser processes being killed mid-test, producing...

A Playwright strict mode violation means the locator you used resolved to more than one element, but the operation requi...

The error "Target page, context or browser has been closed" surfaces when Playwright tries to interact with a page, fram...

Playwright runs headless by default — the browser launches without a visible UI, which is faster and what CI environment...

npm package '@playwright/mcp@latest' is not installed in the npx cache shows up when an MCP client (Claude Desktop, Clau...

-32603 is the generic JSON-RPC "Internal error" code, and when the Playwright MCP server returns it with the message "ta...