Error map

NSURLErrorServerCertificateUntrusted (-1202) iOS: Error Domain=NSURLErrorDomain Code=-1202 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be 'example.com'"

SSL / TLS · layer 2, Network

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1 · On your device 2 · Network 3 · Edge & web server 4 · Application & API 6 · Platform & cloud
NSURLErrorServerCertificateUntrusted (-1202) — iOS: Error Domain=NSURLErrorDomain Code=-1202 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be 'example.com'" (SSL / TLS)NSURLErrorS…A TLS error caused the secure connection to fail — Safari: Safari Can’t Open the Page — A TLS error caused the secure connection to fail (Browser)A TLS error caused …SSLCertificateFile: file does not exist — Apache: AH02240: Server should be SSL-aware but has no certificate configured / SSLCertificateFile: file '/etc/ssl/x.crt' does not exist or is empty (SSL / TLS)SSLCertificateFile:…Certificate pinning failure! — Android/OkHttp: javax.net.ssl.SSLPeerUnverifiedException: Certificate pinning failure! Peer certificate chain: sha256/... Pinned certificates for api.example.com (SSL / TLS)Certificate pinning…incomplete certificate chain — SSL Labs: Chain issues: Incomplete — Extra download (intermediate certificate missing) (SSL / TLS)incomplete certific…AH01909: server certificate does NOT include an ID which matches the server name — Apache: [ssl:warn] AH01909: example.com:443:0 server certificate does NOT include an ID which matches the server name (SSL / TLS)AH01909: server cer…Timeout during connect (likely firewall problem) — Let's Encrypt: Fetching http://example.com/.well-known/acme-challenge/token: Timeout during connect (likely firewall problem) (SSL / TLS)Timeout during conn…CAA record forbids issuance — Let's Encrypt/CA: CAA record for example.com prevents issuance (SSL / TLS)CAA record forbids …ERR_CERT_AUTHORITY_INVALID — NET::ERR_CERT_AUTHORITY_INVALID (Your connection is not private) (JavaScript)ERR_CERT_AUTHORITY_…ERR_CERT_DATE_INVALID — NET::ERR_CERT_DATE_INVALID (certificate expired) (JavaScript)ERR_CERT_DATE_INVAL…ERR_CONNECTION_CLOSED — Chrome: This site can’t be reached — example.com unexpectedly closed the connection. ERR_CONNECTION_CLOSED (Browser)ERR_CONNECTION_CLOS…ERR_TOO_MANY_REDIRECTS (Cloudflare) — ERR_TOO_MANY_REDIRECTS with Cloudflare (Flexible SSL redirect loop) (Cloudflare)ERR_TOO_MANY_REDIRE…ERR_SSL_VERSION_OR_CIPHER_MISMATCH (Cloudflare) — ERR_SSL_VERSION_OR_CIPHER_MISMATCH on a Cloudflare site (certificate not issued / multi-level subdomain) (Cloudflare)ERR_SSL_VERSION_OR_…Cloudflare Origin CA not trusted — NET::ERR_CERT_AUTHORITY_INVALID with a Cloudflare Origin Certificate (record not proxied) (Cloudflare)Cloudflare Origin C…HandshakeException: CERTIFICATE_VERIFY_FAILED — Dart: HandshakeException: Handshake error in client (OS Error: CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate) (Flutter / Dart)HandshakeException:…gRPC: Ssl handshake failed / authentication handshake failed — gRPC: rpc error: code = Unavailable desc = connection error: desc = "transport: authentication handshake failed: x509: certificate signed by unknown authority" (SSL / TLS)gRPC: Ssl handshake…ERR_INVALID_ARG_TYPE — TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined (Node.js)ERR_INVALID_ARG_TYPEImproperlyConfigured — django.core.exceptions.ImproperlyConfigured: settings are not configured / SECRET_KEY must not be empty (Python)ImproperlyConfiguredDisallowedHost — django.core.exceptions.DisallowedHost: Invalid HTTP_HOST header: 'x'. You may need to add 'x' to ALLOWED_HOSTS. (Python)DisallowedHostAH00558 — Apache: AH00558: apache2: Could not reliably determine the server's fully qualified domain name (Nginx / Apache)AH00558SEC_ERROR_EXPIRED_CERTIFICATE — Firefox: Peer's Certificate has expired. Error code: SEC_ERROR_EXPIRED_CERTIFICATE (SSL / TLS)SEC_ERROR_EXPIRED_C…SSL_ERROR_BAD_CERT_DOMAIN — Firefox: Websites prove their identity via certificates — the certificate is only valid for other names. Error code: SSL_ERROR_BAD_CERT_DOMAIN (SSL / TLS)SSL_ERROR_BAD_CERT_…1020 — Cloudflare Error 1020: Access Denied (Cloudflare)1020ssh port 22 Connection timed out — ssh: connect to host x port 22: Connection timed out (Linux)ssh port 22 Connect…No route to host — connect: No route to host (EHOSTUNREACH) (Linux)No route to hostsudo: unable to resolve host — sudo: unable to resolve host <hostname>: Name or service not known (Linux)sudo: unable to res…Temporary failure in name resolution — ping: google.com: Temporary failure in name resolution (Linux)Temporary failure i…523 — Cloudflare Error 523: Origin is unreachable (Cloudflare)523

Directly related (7)

A TLS error caused the secure connection to failBrowser

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…

SSLCertificateFile: file does not existSSL / TLS

Apache: AH02240: Server should be SSL-aware but has no certificate configured / SSLCertificateFile: file '/etc/ssl/x.crt' does not exist or is empty

Apache cannot find the certificate or key file named in its configuration, or `SSLEngine on` is set without any certificate.

Certificate pinning failure!SSL / TLS

Android/OkHttp: javax.net.ssl.SSLPeerUnverifiedException: Certificate pinning failure! Peer certificate chain: sha256/... Pinned certificates for api.example.com

The app's pinned certificate/public-key hash does not match the one the server presented, so OkHttp blocked the request.

incomplete certificate chainSSL / TLS

SSL Labs: Chain issues: Incomplete — Extra download (intermediate certificate missing)

The server sends only its own certificate and not the intermediate CA(s), so some clients cannot build a trusted chain.

AH01909: server certificate does NOT include an ID which matches the server nameSSL / TLS

Apache: [ssl:warn] AH01909: example.com:443:0 server certificate does NOT include an ID which matches the server name

Apache's SSL virtual host name does not match any name inside the certificate it loads.

Timeout during connect (likely firewall problem)SSL / TLS

Let's Encrypt: Fetching http://example.com/.well-known/acme-challenge/token: Timeout during connect (likely firewall problem)

The ACME validation server could not reach your server on port 80 within the timeout.

CAA record forbids issuanceSSL / TLS

Let's Encrypt/CA: CAA record for example.com prevents issuance

The domain's DNS CAA records do not list the certificate authority you asked, so the CA must refuse.

Two steps away (20)

ERR_CERT_AUTHORITY_INVALIDJavaScript

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.

ERR_CERT_DATE_INVALIDJavaScript

NET::ERR_CERT_DATE_INVALID (certificate expired)

The site’s certificate has expired (or isn’t valid yet) — or the device clock is wrong.

ERR_CONNECTION_CLOSEDBrowser

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,…

ERR_TOO_MANY_REDIRECTS (Cloudflare)Cloudflare

ERR_TOO_MANY_REDIRECTS with Cloudflare (Flexible SSL redirect loop)

The page redirects to itself forever — classic cause: Cloudflare SSL mode “Flexible” while the origin redirects HTTP to HTTPS.

ERR_SSL_VERSION_OR_CIPHER_MISMATCH (Cloudflare)Cloudflare

ERR_SSL_VERSION_OR_CIPHER_MISMATCH on a Cloudflare site (certificate not issued / multi-level subdomain)

Cloudflare has no edge certificate for the hostname — the Universal SSL cert is still pending, or the hostname is a second-level…

Cloudflare Origin CA not trustedCloudflare

NET::ERR_CERT_AUTHORITY_INVALID with a Cloudflare Origin Certificate (record not proxied)

Cloudflare Origin CA certificates are only trusted by Cloudflare — visitors reaching the origin directly (grey-cloud record, dire…

HandshakeException: CERTIFICATE_VERIFY_FAILEDFlutter / Dart

Dart: HandshakeException: Handshake error in client (OS Error: CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate)

The app refused the server's TLS certificate because it is self-signed, expired, missing intermediates, or the device clock/CA st…

gRPC: Ssl handshake failed / authentication handshake failedSSL / TLS

gRPC: rpc error: code = Unavailable desc = connection error: desc = "transport: authentication handshake failed: x509: certificate signed by unknown authority"

A gRPC client could not complete TLS to the server — untrusted certificate, name mismatch, or plaintext/TLS mismatch.

ERR_INVALID_ARG_TYPENode.js

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined

A Node API got an argument of the wrong type — usually undefined because an env var or config value is missing.

ImproperlyConfiguredPython

django.core.exceptions.ImproperlyConfigured: settings are not configured / SECRET_KEY must not be empty

Django can’t load its settings — DJANGO_SETTINGS_MODULE unset, a required setting missing, or an environment variable not provide…

DisallowedHostPython

django.core.exceptions.DisallowedHost: Invalid HTTP_HOST header: 'x'. You may need to add 'x' to ALLOWED_HOSTS.

The request’s Host header isn’t listed in Django’s ALLOWED_HOSTS.

AH00558Nginx / Apache

Apache: AH00558: apache2: Could not reliably determine the server's fully qualified domain name

A harmless startup warning: Apache has no global ServerName, so it guessed one from the host’s IP.

SEC_ERROR_EXPIRED_CERTIFICATESSL / TLS

Firefox: Peer's Certificate has expired. Error code: SEC_ERROR_EXPIRED_CERTIFICATE

Firefox found an expired certificate in the chain presented by the server.

SSL_ERROR_BAD_CERT_DOMAINSSL / TLS

Firefox: Websites prove their identity via certificates — the certificate is only valid for other names. Error code: SSL_ERROR_BAD_CERT_DOMAIN

The certificate does not include the hostname you typed.

1020Cloudflare

Cloudflare Error 1020: Access Denied

A Cloudflare firewall/WAF custom rule blocked the request — the visitor’s IP, country, user agent or request pattern matched a bl…

ssh port 22 Connection timed outLinux

ssh: connect to host x port 22: Connection timed out

SSH packets get no reply — a firewall/security group drops them, the server is off, or the IP is wrong.

No route to hostLinux

connect: No route to host (EHOSTUNREACH)

The destination host isn’t reachable — it’s down, on another subnet without routing, or a firewall rejects with “host unreachable…

sudo: unable to resolve hostLinux

sudo: unable to resolve host <hostname>: Name or service not known

The machine’s hostname isn’t in /etc/hosts (or DNS), so sudo prints this warning — usually after changing the hostname.

Temporary failure in name resolutionLinux

ping: google.com: Temporary failure in name resolution

The Linux host can’t resolve domain names — no working DNS server is configured or reachable.

523Cloudflare

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…

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