high

CypressError: An uncaught error was detected outside of a test

The application under test threw an uncaught JavaScript error. Cypress catches these and fails the test to alert you of application bugs.

Common Causes

  1. 1Application has a JavaScript error (null reference, undefined variable)
  2. 2Third-party script threw an error
  3. 3Browser extension injected faulty code
  4. 4API returned unexpected data causing a crash

How to Fix

Ignore known third-party errors

// cypress/support/e2e.ts
Cypress.on('uncaught:exception', (err) => {
  // Ignore known third-party errors
  if (err.message.includes('ResizeObserver')) return false;
  if (err.message.includes('gtag')) return false;
  // Let real errors fail the test
  return true;
});

Filter out known third-party errors while still catching real application bugs.

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Related Errors

CypressError: cy.visit() failed

cy.visit() failed to load the target URL. The server may be unreachable, or the response status code indicates an error.

AssertionError: expected true to equal false

A Chai assertion in Cypress failed because the actual value did not match the expected value. This is the most common test failure type.

CypressError: Timed out retrying after 4000ms

A Cypress command timed out while retrying. Cypress automatically retries assertions until the timeout, then fails. The default is 4 seconds.

CypressError: Expected to find element but never found it

Cypress could not find any element matching the selector within the timeout period. The element may not exist, may have a different selector, or may not have been rendered yet.

CypressError: element has been detached from the DOM

The element that Cypress was interacting with was removed from the DOM and re-rendered. This is common in React/Vue/Angular apps where components re-render.