HTTP Status Code

You might say

The page opens to a 404 error. Did I write the wrong link, or was the deployment incomplete?

A three-digit answer from the server about a request: success, redirect, a request problem, or a server failureWhen a page fails, a 404 response says the target resource was not found; check the URL, route, and deployment. A 500 is a server-error-class response; correlate its request ID with server logs to find clues. A status code points to the next check but does not prove the root cause or responsibility on its own.

Know first

HTTP Deployment

Status Code

The same page problem, with the status code pointing to which side to check

example.com/save

GET/old-page404The server has no such resource

POST/save500The server failed while handling it

GET/dashboard401The identity was not accepted

GET/home200This request succeeded

500 · The server failed while handling itServer

Check server logs for this request; the page message cannot replace the status code

Use the buttons above to switch status-code scenarios. The first digit groups the outcome (2xx success, 3xx redirect, 4xx client error, 5xx server error); the exact number narrows the cause.

How status codes guide where to look

Read the category first: The first digit groups response classes: 2xx success, 3xx redirection, 4xx client error, and 5xx server error. This guides the next check; use the request and logs to locate a cause.

The exact number narrows the cause: A 404 response says the target resource was not found, 401 means valid authentication credentials are missing, and 400 signals a problem with the request. Check the URL, request, and response for the cause.

Where to find it: The browser Network panel records the status code of every request; debugging tools and errors reported by AI agents also print the number directly.

Quick checkChoose the best answer

A form shows a generic network error, and the Network panel reports 500. What should happen first?

Inspect frontend code first because the page renders the messageTreat 500 as a server-side failure and check server logs for this requestRetry repeatedly because the page message says network error

You can say this to an AI Agent

The page returns 404 and the form returns 500. Check each URL, status, and response in Network; review the route or deployment for the 404, and correlate the 500 request ID with server logs. After fixing it, resend and verify the page and saved data.

Learn next

1Browser DevTools→2HTTP→3Server Logs→

Recommended tool

Web fine-tuning tool · Selector Pro

Select page elements for precise AI edits

Click a button, text, or card, note the change, then copy its exact location to AI.

Open Selector Pro website