~/devtools / http-status / 304
tool::http-status-detail

304 Not Modified

The cached version is still valid; no new content to return.

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Status Code
304
Name
Not Modified
Category
3xx

Detailed Explanation

HTTP 304 Not Modified indicates that the client's cached version of the resource is still valid. It is returned in response to a conditional request (If-None-Match or If-Modified-Since) when the resource has not changed. This saves bandwidth and significantly improves page load speed by eliminating unnecessary data transfer.

Common Causes
  • A browser sends a conditional GET to validate a cached resource
  • ETag or Last-Modified based cache validation finds no changes
  • A CDN checks the origin server for content changes
  • An API client polls for changes using conditional requests
How to Fix
  • 1.304 is normal behavior — no fix needed
  • 2.To force fetching the latest version, use Ctrl+Shift+R (hard refresh)
  • 3.Use Cache-Control: no-cache to always revalidate with the server
  • 4.During development, disable cache in browser DevTools to avoid stale data

Related HTTP Headers

ETagLast-ModifiedCache-ControlExpires

Response Example

HTTP/1.1 304 Not Modified
ETag: "abc123"
Cache-Control: max-age=3600

Related Status Codes

300Multiple ChoicesMultiple options for the requested resource.301Moved PermanentlyThe resource has permanently moved to a new URL.302FoundThe resource is temporarily at a different URL.303See OtherRedirect to another resource using GET.307Temporary RedirectTemporary redirect preserving the original HTTP method.
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