Error map
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WordPress · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (11). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (11)
WordPress: 403 Forbidden on wp-admin, wp-login.php or admin-ajax.php
The server or a security layer refused access to WordPress admin URLs — file permissions, a security plugin/WAF rule, ModSecurity…
WordPress: Are you sure you want to do this? Please try again. (nonce check failed)
A WordPress security nonce didn’t validate — the page was open too long, cached, or a plugin/theme form is broken.
WordPress: Another update is currently in progress.
WordPress thinks an update is running because the core_updater.lock option exists — usually left behind by a failed/interrupted u…
Warning: Cannot modify header information - headers already sent
You called `header()`, `setcookie()` or `session_start()` after output had already been sent to the browser.
WordPress: ERR_TOO_MANY_REDIRECTS / redirected you too many times on wp-admin or the whole site
WordPress and the server/proxy keep redirecting to each other — usually siteurl/home mismatch (http vs https, www vs non-www) or…
OIDC Error: login_required / interaction_required / consent_required (silent authentication failed)
A silent sign-in (prompt=none, iframe or refresh) couldn’t complete because the user must interact — no session, consent needed,…
OAuth callback error: state mismatch / Unable to verify authorization request state / State cookie was missing
The state value returned to the callback doesn’t match what the app stored before redirecting — the CSRF protection for OAuth fai…
HTTP 431 Request Header Fields Too Large
The request headers — almost always cookies — exceed the server’s size limit.
WordPress: 404 Not Found on every page except the homepage (permalinks / .htaccess / Nginx rules)
Pretty permalinks aren’t being routed to index.php — .htaccess is missing/ignored (Apache) or Nginx lacks try_files.
This Set-Cookie was blocked because it had the "SameSite=Lax" attribute but came from a cross-site response / SameSite=None requires Secure
The browser refused to store or send an auth/session cookie because of SameSite or Secure rules — so logins don’t “stick” across…
WooCommerce: Sorry, your session has expired. Return to shop
WooCommerce lost the customer’s cart session — usually because checkout/cart pages are cached or cookies are blocked/stripped.
Two steps away (33)
HTTP 403 Forbidden
The server understood the request but refuses to authorize it — you (or the server process) are not allowed to access this resour…
Webhook signature verification failed (Stripe, Razorpay, GitHub…)
Your endpoint computed a different HMAC signature than the one the provider sent, so the webhook is rejected.
WordPress: Sorry, you are not allowed to access this page.
Your user role lacks the capability for that admin screen — or the database table prefix / user capabilities are out of sync afte…
WordPress: The link you followed has expired
Usually an upload (theme, plugin, media) larger than PHP’s upload/post limits — WordPress receives an empty request and shows thi…
WordPress: Updating failed. The response is not a valid JSON response.
The block editor saved via the REST API but got HTML or an error page back — broken permalinks, a security plugin/WAF, or PHP out…
java.lang.SecurityException: Permission Denial ... requires android.permission.X
The app called an API that needs a permission it hasn’t declared or the user hasn’t granted at runtime.
WordPress: Briefly unavailable for scheduled maintenance. Check back in a minute.
An update was interrupted and WordPress left its `.maintenance` file behind, so the site stays in maintenance mode.
WordPress: Missed schedule — scheduled posts not publishing (WP-Cron not running)
WP-Cron didn’t fire at the scheduled time, so scheduled posts and tasks (backups, emails, WooCommerce jobs) are late.
WordPress block editor: The editor has encountered an unexpected error (Attempt Recovery / Copy Error)
A JavaScript error broke the block editor — usually a plugin/theme block script conflict, cached old scripts, or a browser extens…
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
PHP Fatal error: Uncaught Error: Call to undefined function
PHP can’t find the function you called — usually a missing extension, missing include, or namespace issue.
Warning: Undefined array key / Undefined index
Your code reads an array key that doesn’t exist — common with `$_GET`, `$_POST` and decoded JSON.
HTTP 301 Moved Permanently
The resource has a new permanent URL; clients and search engines should use the address in the Location header from now on.
HTTP 302 Found (Temporary Redirect)
The resource is temporarily at another URL; clients should keep using the original URL for future requests.
HTTP 303 See Other
A redirect telling the client to fetch the result from another URL with GET — used after a form POST so refreshing doesn’t resubm…
AWS: ExpiredToken — The security token included in the request is expired
Temporary AWS credentials (STS/SSO/assumed role) have expired.
OAuth 2.0 Error: invalid_grant
The authorization code, refresh token or credentials sent to the token endpoint are invalid, expired, already used or were issued…
Warning: session_start(): Session cannot be started after headers have already been sent
session_start() ran after output was sent, so PHP can’t set the session cookie.
Laravel: 419 Page Expired (CSRF token mismatch)
Laravel rejected a POST because the CSRF token was missing, expired or didn’t match the session.
Forbidden (403) CSRF verification failed. Request aborted.
Django rejected a POST because the CSRF token was missing, wrong, or the request origin isn’t trusted.
OAuth PKCE error: invalid_grant — PKCE verification failed / code_verifier does not match code_challenge / code_challenge required
The code_verifier sent to the token endpoint doesn’t match the code_challenge from the authorize request, or PKCE is required but…
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
HTTP 414 URI Too Long
The request URL (usually the query string) is longer than the server will accept.
HTTP 404 Not Found
The server can’t find anything at the requested URL.
FastCGI sent in stderr: "Primary script unknown"
Nginx passed a script path to PHP-FPM that PHP-FPM couldn’t find — usually a wrong SCRIPT_FILENAME or root.
Nginx 444 No Response (connection closed without response)
An Nginx-specific code: the server deliberately closed the connection without sending anything — a rule is dropping the request.
CORS Error: No 'Access-Control-Allow-Origin' header is present
The browser blocked a cross-origin request because the server’s response didn’t include the CORS headers allowing your site’s ori…
Mixed Content: The page was loaded over HTTPS, but requested an insecure resource
An HTTPS page tried to load a script, API or image over plain HTTP, and the browser blocked (or warned about) it.
SecurityError: Blocked a frame with origin "x" from accessing a cross-origin frame.
Script tried to read or modify an iframe (or window) from another origin.
HTTP 304 Not Modified
The cached copy is still valid, so the server sends no body and the client reuses its cache.
HTTP 412 Precondition Failed
A conditional request header (If-Match, If-Unmodified-Since) didn’t match the current state of the resource.
Cloudflare Error 1200: Cache connection limit
Too many requests are queued at Cloudflare for the origin — the origin is slow and connections pile up.
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