Error map
Certificate pinning failure! Android/OkHttp: javax.net.ssl.SSLPeerUnverifiedException: Certificate pinning failure! Peer certificate chain: sha256/... Pinned certificates for api.example.com
SSL / TLS · layer 2, Network
Centre: this error. First ring: errors it is linked with (7). 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 (7)
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…
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.
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.
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'"
iOS rejected the server's certificate (untrusted issuer, name mismatch, expired, or weak).
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.
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.
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)
android.os.NetworkOnMainThreadException
The app made a network call on the main (UI) thread, which Android forbids.
Error Domain=NSURLErrorDomain Code=-1009 "The Internet connection appears to be offline."
URLSession couldn’t reach the network — the device is offline, the app’s cellular data is disabled, or the simulator lost network…
Error Domain=NSURLErrorDomain Code=-1001 "The request timed out."
The server didn’t respond within URLSession’s timeout (60 s default) — slow server, unreachable host on this network, or a stalle…
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 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…
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…
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.
Firefox: Peer's Certificate has expired. Error code: SEC_ERROR_EXPIRED_CERTIFICATE
Firefox found an expired certificate in the chain presented by the server.
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.
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…
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.
Go: x509: certificate signed by unknown authority
The Go TLS client does not trust the CA that signed the server's certificate.
Go: x509: certificate is valid for www.example.com, not api.example.com
The server's certificate does not list the hostname you connected to (SAN mismatch), or it has expired.
OpenSSL: error:1408F10B:SSL routines:ssl3_get_record:wrong version number
The peer did not answer with a TLS record — you spoke TLS to a plain HTTP/SMTP port (or the reverse), or a proxy intervened.
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: 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.
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 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.
ping: google.com: Temporary failure in name resolution
The Linux host can’t resolve domain names — no working DNS server is configured or reachable.
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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