Error map
ERR_CACHE_MISS ERR_CACHE_MISS: Confirm Form Resubmission
Browser · layer 1, On your device
Centre: this error. First ring: errors it is linked with (12). 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 (12)
ERR_CONNECTION_TIMED_OUT: This site can’t be reached — example.com took too long to respond
The browser waited for the server but got no response — the server is down/unreachable, a firewall drops traffic, or DNS points t…
TypeError: Failed to fetch / NetworkError when attempting to fetch resource
The browser couldn’t complete the request at the network level — CORS, DNS, offline, blocked mixed content, or the server refused…
ERR_CONNECTION_RESET: This site can’t be reached — The connection was reset
The connection to the website was cut off mid-way — by the server, a firewall/antivirus, a VPN/proxy, or network equipment.
ERR_SSL_PROTOCOL_ERROR (This site can't provide a secure connection)
The browser couldn’t negotiate TLS — the server sent an invalid response, often plain HTTP on the HTTPS port.
Contact Form 7: There was an error trying to send your message. Please try again later.
The form submitted, but wp_mail() failed to send — the server can’t send mail or the mail settings are wrong.
Firebase Auth: auth/popup-closed-by-user / auth/popup-blocked / auth/cancelled-popup-request
The OAuth popup for Google/GitHub sign-in was closed, blocked by the browser, or replaced by another popup request.
QuotaExceededError: Failed to execute 'setItem' on 'Storage': Setting the value exceeded the quota
localStorage/sessionStorage is full (about 5 MB per origin) or storage is disabled.
NET::ERR_CERT_AUTHORITY_INVALID (Your connection is not private)
The site’s certificate isn’t signed by a CA the browser trusts — self-signed, missing intermediates, or intercepted by a proxy.
NotAllowedError: Failed to execute 'writeText' on 'Clipboard': Document is not focused.
The Clipboard API refused to write — the page isn’t focused, there was no user gesture, or the context isn’t secure.
NET::ERR_CERT_DATE_INVALID (certificate expired)
The site’s certificate has expired (or isn’t valid yet) — or the device clock is wrong.
Warning: A component is changing an uncontrolled input to be controlled
An input’s `value` started as `undefined` (uncontrolled) and later became a defined value (controlled), or vice versa.
NotAllowedError: play() failed because the user didn't interact with the document first.
The browser blocked media autoplay with sound until the user interacts with the page.
Two steps away (36)
Error: connect ECONNREFUSED 127.0.0.1:5432
Nothing is listening at that host:port — the target service is down or you’re connecting to the wrong address.
HTTP 407 Proxy Authentication Required
A proxy between you and the server requires credentials before it will forward your request.
HTTP 408 Request Timeout
The server closed the connection because the client took too long to send the complete request.
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
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…
SSL: CERTIFICATE_VERIFY_FAILED / unable to get local issuer certificate
The client couldn’t verify the server’s TLS certificate chain, so it refused the HTTPS connection.
API Request Timed Out (ETIMEDOUT / ReadTimeout / timeout of 30000ms exceeded)
The client gave up waiting — either for the connection to open or for the response to arrive.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
Error: getaddrinfo ENOTFOUND host / Name or service not known
DNS lookup for the hostname failed — the name is wrong, doesn’t exist, or this machine can’t resolve it.
Cloudflare Error 525: SSL Handshake Failed
Cloudflare couldn’t complete a TLS handshake with your origin (SSL mode Full / Full strict).
javax.net.ssl.SSLHandshakeException: PKIX path building failed: unable to find valid certification path to requested target
Java doesn’t trust the server’s certificate chain (self-signed, corporate proxy CA, or missing intermediate).
net::ERR_BLOCKED_BY_CLIENT
A browser extension (ad blocker, privacy tool) blocked the request.
PHP mail() returns false / emails not delivered
PHP’s mail() function failed or emails never arrive (spam or rejected).
SES MessageRejected: Email address is not verified. The following identities failed the check in region
SES refused to send because the From address/domain isn’t verified — or the account is still in the SES sandbox, where recipients…
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.
Azure AD (Entra ID): AADSTS700016 Application not found in the directory
The client ID in your sign-in request doesn’t exist in the tenant you’re authenticating against.
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…
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
Azure Storage: AuthorizationPermissionMismatch (403) — This request is not authorized to perform this operation using this permission
You’re accessing blob/queue data with Microsoft Entra ID, but the identity has only management roles (Owner/Contributor) — not a…
net::ERR_CONNECTION_REFUSED (This site can't be reached — refused to connect)
The browser reached the host but nothing was listening on that port.
net::ERR_NAME_NOT_RESOLVED (This site can't be reached — server IP address could not be found)
DNS couldn’t resolve the hostname in the browser.
net::ERR_ABORTED 404 (Not Found)
The browser cancelled the request — often because it returned an error (404) or the page navigated away.
ResizeObserver loop completed with undelivered notifications.
A ResizeObserver callback changed layout in a way that triggered another resize in the same frame.
Error [ERR_TLS_CERT_ALTNAME_INVALID]: Hostname/IP does not match certificate's altnames
The server’s certificate doesn’t cover the hostname you connected to.
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
The docker CLI can’t talk to the Docker engine — it isn’t running, or your user can’t access the socket.
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…
OAuth 2.0 Error: invalid_scope / insufficient_scope
The requested scope is unknown or not allowed for this client — or the token lacks the scope the API endpoint requires.
Cloudflare Error 526: Invalid SSL Certificate
With SSL mode Full (strict), the origin’s certificate is expired, self-signed, or doesn’t match the hostname.
SSL error: tlsv1 alert protocol version / unsupported protocol / no protocols available
The client and server couldn’t agree on a TLS version or cipher, so the HTTPS handshake failed before any HTTP was exchanged.
ACM certificate stuck in Pending validation
ACM is waiting to see the DNS (or email) validation record — it wasn’t created, was created in the wrong DNS zone, or has a typo.
TypeError: Cannot read properties of undefined (reading 'x')
You tried to access a property on a value that is `undefined` (or `null`) — usually data that hasn’t loaded yet or a wrong proper…
Error: Too many re-renders. React limits the number of renders to prevent an infinite loop.
A state update runs during render, which triggers another render, which updates state again — forever.
TypeError: Cannot assign to read only property 'x' of object
Code tried to modify a frozen object, a getter-only property, or immutable state.
WordPress: Sorry, you are not allowed to upload this file type / Sorry, this file type is not permitted for security reasons
WordPress blocked the upload because the file extension/MIME type isn’t in its allowed list (SVG, JSON, WEBP on old versions, fon…
WordPress Media: “HTTP error.” when uploading images
The upload request failed on the server — memory or timeout during image processing, upload size limits, ModSecurity, or Imagick…
WordPress: Post-processing of the image failed likely because the server is busy or does not have enough resources
The image uploaded but WordPress couldn’t generate its resized versions — memory/CPU limits or Imagick problems.
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