My website has errors I can't see. How do I find them?
Updated 2026-10-17
Short answer: most website errors are invisible to the owner. A script error can stop a button or form working while the page looks fine, and other pages can return server errors (5xx) or not-found (404) to visitors while your homepage loads normally for you.
How to check it yourself
- Open your important pages (contact, checkout, sign-up) in a private window.
- Open developer tools, then Console, reload, and look for red errors.
- If your site is on Cloudflare, open your domain, then Analytics, and look at responses by status code, filtered to 5xx and 404, to see which addresses fail.
- Match the time errors started against your last changes or updates.
What Preventionlabs shows
Every report opens your homepage and up to 3 more pages from your sitemap in a real Chrome browser, as a visitor would, and reports uncaught JavaScript errors and requests the browser blocks under CORS. Nothing is clicked, typed or submitted. With a read-only Cloudflare token connected, it also shows the server errors (5xx) and not-found (404) responses visitors got, by address, as Cloudflare counted them. For example, from a real report: "36 server error responses out of 943 requests in the last 24 hours (3.8%) ... / (29 x 523), / (4 x 521), / (3 x 520)".
Errors that only happen after clicking or typing need the console steps above.
Price
First report free, no card needed. Then A$50 a month, up to 10 domains.