Is it safe to retry after a 408?
Usually yes. The server never processed the request because it never arrived completely, so repeating it on a fresh connection is the expected response.
HTTP 408 REQUEST TIMEOUT
The client took too long to send the request. 408 belongs to the 4xx client error class and is defined in RFC 9110.
Loading the workbench.
About HTTP 408
What Does HTTP 408 Request Timeout Mean?
The client took too long to send the request. The code is registered with IANA and defined in RFC 9110.
Client error: the request has a problem, so it cannot be fulfilled as sent. Every code from 400 to 499 shares that general meaning, so a client that does not recognise 408 must treat it like 400.
When Do You See a 408 Response?
408 Request Timeout means the server gave up waiting for the client to finish sending its request. Slow uploads over poor connections, clients that open a connection and never send anything, and browser preconnects left idle can all trigger it. Some servers send 408 just before closing an idle keep-alive connection. It differs from 504, where a gateway waited too long for an upstream server rather than for the client.
How Do You Fix a 408?
Clients can retry, ideally on a new connection, since the request never completed and is safe to send again. Most browsers retry automatically. For large uploads, compress data, split it into chunks, or use resumable uploads. Servers should send Connection: close with a 408, and may raise their client body timeout if legitimate clients on slow networks are being cut off.
What Does a 408 Response Look Like?
HTTP/1.1 408 Request Timeout
Connection: close
Content-Length: 0408 is not cacheable by default: a browser or CDN stores it only when Cache-Control or Expires explicitly allows it.
To inspect a real one without sending it anywhere:
- Copy the response headers from your browser Network tab, or from
curl -i. - Paste them into the Header decoder to see every header explained.
- Check caching in the Cache lane.
Which Status Codes Are Related to 408?
- 504 Gateway Timeout: A proxy or gateway gave up waiting for the upstream server.
- 413 Content Too Large: The body is bigger than the server accepts. Formerly "Payload Too Large".
- 400 Bad Request: The request is malformed: bad syntax, invalid framing, or an unreadable body.
Browse every code on the HTTP status codes page.
What Other Lanes Are in the Reference Section?
- HTTP status codes: Every IANA-registered status code, with a page per code.
- MIME types: File extensions to Content-Type, searchable both ways, plus a Content-Type parser.
- HTTP methods: GET, POST, PUT, PATCH, DELETE and the rest: safe, idempotent, cacheable.
Elsewhere in 2http: Header decoder, Cookie decoder, Cache-Control decoder, CORS checker, User-agent parser, and all eleven lanes on the 2http home page. Part of the 2suite.io privacy-first ecosystem.
Frequently Asked Questions
What is the difference between 408 and 504?
408 means the server waited too long for the client. 504 means a gateway or proxy waited too long for the upstream server.
Is HTTP 408 an error?
Yes. 408 is a client error response: the problem is in the request, so repeating it unchanged will usually fail again.
Is a 408 response cacheable by default?
No. Caches store a 408 only when Cache-Control or Expires explicitly allows it.
How Can You Verify That Nothing Leaves This Browser?
You do not have to take our word that your headers stay here. Developer tools show every request a page makes, so you can watch this page work and confirm that nothing is sent. The check takes under a minute.
- Open your browser developer tools with
F12, orCmd+Option+Ion a Mac, and select the Network tab. - Reload the page and let it finish. You will see the page's own files, its web fonts, and one anonymous page-view request. Nothing has been typed yet, so none of them can contain your headers.
- Click the clear icon in the Network tab so that the log is empty.
- Paste real headers into any lane and read the result.
- Look at the Network tab again. It is still empty. For extra proof, turn on offline mode after the page loads and every lane keeps working.
Only two things can add a line to that log, and neither carries your headers. Submitting the feedback form sends the vote and comment you typed. Typing characters in a script the page has not displayed yet, such as Cyrillic or Greek, can make the browser fetch the matching font file, and that request names only the font.
2http never sends a request on your behalf: the request builder writes code for you to run, and the meta inspector reads source you paste instead of fetching a URL. The production site also sends a Content-Security-Policy header that tells your browser to refuse connections to anywhere except this site and the anonymous analytics endpoint.