Error map
SEC_ERROR_UNKNOWN_ISSUER Firefox: Warning: Potential Security Risk Ahead — SEC_ERROR_UNKNOWN_ISSUER (certificate not trusted)
Browser · layer 1, On your device
Centre: this error. First ring: errors it is linked with (9). 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 (9)
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.
NET::ERR_CERT_COMMON_NAME_INVALID: Your connection is not private (certificate is for a different domain)
The certificate presented doesn’t include the hostname you visited — e.g. visiting www.example.com with a certificate only for ex…
Let’s Encrypt / Certbot: Challenge failed for domain example.com — Invalid response from http://example.com/.well-known/acme-challenge/x: 404
Let’s Encrypt couldn’t verify you control the domain — the HTTP-01 challenge file wasn’t served, or DNS points elsewhere.
OpenSSL: unable to load certificate / PEM routines:get_name:no start line (key values mismatch)
OpenSSL (or Nginx/Apache) couldn’t read the certificate or key — wrong file format, wrong file, or the key doesn’t match the cert…
Chrome: This site can’t provide a secure connection — uses an unsupported protocol. ERR_SSL_VERSION_OR_CIPHER_MISMATCH
The browser and the server could not agree on a TLS version or cipher — the server is too old or misconfigured, or the browser is.
Chrome: Your connection is not private — NET::ERR_CERT_REVOKED (the certificate was revoked)
The site’s TLS certificate has been revoked by the certificate authority, so browsers refuse to trust it.
Firefox: Secure Connection Failed — SSL_ERROR_NO_CYPHER_OVERLAP (no common cipher)
Firefox and the server share no TLS cipher suite, so the secure handshake cannot even start.
Firefox: The page isn’t redirecting properly — Firefox has detected that the server is redirecting the request in a way that will never complete
Firefox's wording for a redirect loop (Chrome calls it ERR_TOO_MANY_REDIRECTS).
Firefox: Hmm. We’re having trouble finding that site. / Server not found (DNS_PROBE or NS_ERROR_UNKNOWN_HOST)
Firefox could not resolve the website’s hostname to an IP address — a typo, a DNS problem or no internet.
Two steps away (22)
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.
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).
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.
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.
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.
Provisioning profile "x" doesn't include signing certificate "Apple Development: Name (ID)"
The profile was created with a different certificate than the one installed in your keychain.
Error: error:0308010C:digital envelope routines::unsupported
An old build tool (webpack 4, old react-scripts) uses a hash algorithm that OpenSSL 3 in Node 17+ disables.
Nginx: nginx: [emerg] unknown directive "x" in /etc/nginx/sites-enabled/x:12 — configuration file test failed
Nginx found a directive it doesn’t know — a typo, a missing semicolon on the previous line, a directive from a module that isn’t…
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.
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.
Chrome: This site can’t be reached — example.com unexpectedly closed the connection. ERR_CONNECTION_CLOSED
The server closed the connection before finishing the TLS handshake or sending a response — typical for HTTP/HTTPS port mix-ups,…
Cloudflare Error 525: SSL Handshake Failed
Cloudflare couldn’t complete a TLS handshake with your origin (SSL mode Full / Full strict).
NET::ERR_CERT_DATE_INVALID (certificate expired)
The site’s certificate has expired (or isn’t valid yet) — or the device clock is wrong.
Chrome: Connection not secure — ERR_SSL_OBSOLETE_VERSION (old TLS 1.0/1.1)
The server only supports an outdated TLS version that current browsers no longer allow.
Chrome: You cannot visit example.com right now because the website uses HSTS (NET::ERR_CERT_… no bypass)
The site told browsers to use only valid HTTPS (HSTS), so Chrome hides the "Proceed anyway" link when its certificate has any pro…
Safari: Safari Can’t Open the Page — A TLS error caused the secure connection to fail
Safari could not set up a secure TLS connection — an expired or untrusted certificate, an outdated server configuration or interf…
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…
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.
Cloudflare Error 523: Origin is unreachable
Cloudflare can’t find a network route to your origin server — the DNS record points to a wrong/unroutable IP or the origin networ…
Cloudflare HTTP 530 (with Error 1016 Origin DNS error / 1033 tunnel error)
Cloudflare returns 530 together with a 1xxx error; the 1xxx code (usually 1016 or 1033) tells you the real cause.
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