Todd H. Gardner

Chromium browsers show "Failed to fetch" when requests get no response. Usually CORS issues, ad blockers, or URL typos. Quick fixes: check URL, test in new tab, disable ad blockers.

Safari shows "Load failed" when fetch requests can't connect to servers. Common causes include network issues, CORS problems, or server downtime. Quick fixes: verify URL, check network connection, test in other browsers.

Firefox displays this error when fetch requests encounter connection problems. Often caused by blocked requests, CORS violations, or unreachable servers. Quick fixes: inspect console, verify endpoints, check browser settings.

Generic browser error when cross-origin scripts fail. Caused by Same-Origin Policy blocking error details from external scripts. Quick fixes: add crossorigin attribute, enable CORS headers, check CSP settings.

Error from MetaMask browser extension when it can't detect its own installation. Usually caused by extension conflicts, disabled state, or browser profile issues. Best practice: ignore in error monitoring.

Common JavaScript error when accessing length property on undefined values. Usually occurs with arrays, strings, or API responses that haven't loaded yet. Quick fixes: add null checks, use optional chaining, handle loading states.

JavaScript error when accessing id property on undefined objects. Common with user data, API responses, and array operations. Quick fixes: use optional chaining, check object existence, handle loading states properly.

Empty string error often caused by Pinterest widgets when ad blockers prevent network requests. Results in xhr.statusText being empty instead of descriptive error message. Best practice: ignore Pinterest-related errors.

Confusing error when form elements mask the submit method. Occurs when inputs are named "submit" and override the form's submit function. Quick fixes: rename submit inputs, use prototype method, avoid conflicting names.

Firefox error when external requests are blocked by extensions or CORS issues. Common with AdBlock Plus and antivirus software in older Firefox versions. Primarily affected Firefox until around 2019.

Error signature from CefSharp bot crawlers, often Microsoft Outlook SafeSearch scanning email links. Not a user-facing issue but generates noise in error monitoring. Best practice: ignore this error.

Chrome DevTools warning when trying to access restricted HTTP headers. Not a real JavaScript error - code continues executing normally. Quick fixes: check header availability first, configure CORS to expose headers.

Browser storage error when localStorage or sessionStorage operations fail due to quota limits or private browsing restrictions. Common with "QuotaExceededError" on iOS/macOS private mode. Quick fixes: implement error handling, detect storage availability.

JavaScript errors from search engine bots trying to execute your site's code. Common with Googlebot, Baiduspider, and other crawlers using basic JavaScript engines. Best practice: filter these errors from monitoring.

Network error when Google Analytics tracking requests are blocked by ad blockers or privacy extensions. Common with GA4 collect endpoints. No user impact - represents blocked analytics tracking. Best practice: ignore these errors.

Browser warning when ResizeObserver cannot deliver all observations within a single animation frame. Generally harmless browser optimization - no user impact. Best practice: ignore this error in monitoring.

Get expert solutions to the JavaScript errors that slow you down. Our team breaks down common issues with clear explanations and actionable fixes.

iOS error from Google Translate service when evaluating minified properties. Common on Google App, Safari, and Chrome iOS since June 2025. Originates from translate.googleapis.com script. Safe to ignore - not from your application code.

Axios shows "Network Error" when requests fail due to network connectivity, CORS issues, DNS problems, or ad blockers. Unlike HTTP status errors, this indicates the request never reached the server. Requires investigation and proper error handling.

Chrome extension URLs appearing in JavaScript error stack traces. Indicates errors from browser extensions running on your website. Common with ad blockers, user scripts, and productivity extensions. Safe to ignore - not from your application code.

Firefox extension URLs in JavaScript error stack traces from WebExtensions API. Appears when Firefox add-ons encounter errors while running on your website. Common with privacy extensions, theme managers, and utility add-ons. Can be safely filtered.

WebKit security feature that masks Safari browser extension URLs in error stack traces. Common since 2022, appears as @webkit-masked-url://hidden/ with line numbers. Originates from Safari extensions, not your application code. Safe to ignore.

RangeError thrown when recursive functions exceed browser stack limits. Usually caused by infinite recursion without base cases. Quick fixes: add termination conditions, use iteration instead of recursion, debug with browser DevTools.