In-Browser Runtime

Cypress runs inside the browser and obeys the same-origin policy, so a test is bound to one origin and cannot touch a document from a different one. Wrap the commands for the new origin in a cy.origin() block.

Cypress drives a single tab and has no tab-switching command, so assert the link rather than follow it: check its href and target attributes, request the URL directly with cy.request, or strip the target attribute so the click navigates the current tab.

Spec code is evaluated inside the browser, so console.log() writes to that browser's DevTools console. The terminal belongs to Cypress's separate Node process, which only prints what code in cypress.config.js and its Node handlers log.

Cypress ends the request itself and answers 503, adding an x-cypress-matched-blocked-host header naming the pattern that matched. The request is never sent, so it resolves immediately instead of waiting on a third party.

The bundled Electron browser, unless the project sets defaultBrowser. Electron is deprecated as a test browser in Cypress 16 and will be removed in a future major, so set defaultBrowser or pass --browser to point runs at an installed browser.

The callback is not a closure. Cypress stringifies it, ships it to a second instance of itself running in the other origin and evaluates it there, so the surrounding scope is gone. Data reaches it only through the args option.

Cypress has no hover command. Calling cy.hover() fails with an error saying it is not implemented and links to the workarounds page. Use .trigger('mouseover'), .invoke('show'), a forced action, or the cypress-real-events plugin's realHover for genuine pointer input.

Cypress drives Chrome, Chromium, Edge and the bundled Electron browser over the Chrome DevTools Protocol, and Firefox over WebDriver BiDi. The Node process speaks that protocol; your spec code still runs inside the browser next to the application.

It lands in Cypress's downloadsFolder, cypress/downloads by default, on the machine running Cypress. At launch Cypress tells the browser to save downloads there silently, so no native Save As dialog can block an unattended run.

In Chrome, Chromium and Edge the browser connects to your server directly and Cypress intercepts inside the browser. Firefox, WebKit and Electron still route every request through Cypress's HTTP/1.1 proxy, and forceHttp1 puts every browser back on that path.

Use cy.press(Cypress.Keyboard.Keys.TAB). It sends a real keydown and keyup to the browser through the channel Cypress drives it over, so native focus order applies. Cypress's .type() cannot do it, because it does not support {tab}.

Because the configuration flag is only half of the opt-in. Cypress finds WebKit by resolving Playwright's playwright-webkit package from the project directory, so with the flag set but that package missing there is no WebKit build to list.

Cypress does not support controlling more than one open browser at a time; the spec runs inside the single browser it launched, and no command attaches to another. Cover a two-party flow by driving the second participant from Node with cy.request or cy.task.

cy.request() is issued by the Cypress Node process, not by the browser, so it never passes through the browser network layer where cy.intercept() listens. It reaches the real endpoint every time.

A spec is bundled for the browser before it runs, and a database module depends on Node built-ins the bundler cannot resolve for a browser target. Move that code into a Node handler and call it from the test.

Cypress automates Firefox through WebDriver BiDi, and Firefox builds below 140 implement it incompletely. Cypress 16 marks such a build unsupported and refuses to launch it, naming the version to install. The fix is to update the pinned image or ESR build.

Those commands are not supported inside the callback, because the block runs in a second Cypress instance in the other origin. Declare them outside the block instead: the interception before the navigation, and cy.session() wrapping the whole flow.

cy.origin() handles top-level navigation to another origin, not embedded frames. A cross-origin iframe's contentDocument reads as null under the same-origin policy, so no Cypress command can get a handle on its DOM. Same-origin iframes can be queried.

The plugin registers named Node-side handlers in your Cypress config and adds a cy.puppeteer() command that calls one by name. The handler receives a Puppeteer browser connected to the browser Cypress launched, so it can find and drive the extra page.

The two browsers are on different network paths. As of Cypress 16 Chrome intercepts on the native browser network, where the protocol is negotiated after interception, so httpVersion is undefined. Firefox still proxies through Cypress, which always reported 1.1.

Decide by what the second tab would prove. Assert the handoff and request the URL when the destination is not yours; reach for the puppeteer plugin only when real value lives on the other side and no cheaper seam reaches it.

Reserve cy.press() for behaviour only the browser decides — Tab focus order, Enter activating the focused control, Escape closing a dialog. Keep the cheaper in-page .type() and .trigger() for text entry and for handlers you already know exist.

Rarely, and only for a behaviour no narrower option reaches, such as reading into a cross-origin iframe the app embeds. It works only in Chromium-based browsers, so it quietly pins the suite to one engine and stops testing the browser users have.

Chromium pauses the renderer of a backgrounded tab, so the Cypress tab cannot paint a frame to capture. Cypress therefore activates its own tab before screenshotting, using its browser extension when enabled and force-fronting the tab otherwise, which steals focus in open mode.

The browser launched but Cypress never reached its remote debugging port. On managed machines the usual cause is the RemoteDebuggingAllowed policy set to disabled. Check chrome://policy or edge://policy, and re-run once with a browser the policy does not cover.

Something inside the spec's own import graph is regenerated by each build. The Cypress watcher sees the new file, recompiles, reloads the browser, and the rebuild regenerates the file again. Exclude those generated files from the watcher.

Cypress rewrites obstructive framebusting code in served HTML and JS by default, which changes the file's bytes. The pinned Subresource Integrity hash no longer matches, so the browser refuses the resource. Setting removeSRIAttributes to true strips the attribute.

Pin Chrome for Testing where a red run must mean a real regression, and keep a separate evergreen job so browser changes still reach you. A pin buys reproducibility, not immunity from the next Chrome release, and it needs a bump schedule.

Treat it as a dated migration budget, not a setting. It buys time for specs that cross subdomains after Cypress 14 made every origin change need cy.origin(), but it is deprecated, breaks some identity providers, and will be removed.