Error map
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 · layer 2, Network
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)
Cloudflare Error 1005: Access denied — The owner of this website has banned the autonomous system number (ASN) your IP address is in
The site owner blocked your network provider (ASN) — common for VPNs, cloud/data-center IPs and some mobile carriers.
Cloudflare Error 1006 / 1007 / 1008: Access denied — Your IP address has been banned
The site owner (or a Cloudflare security setting) blocked your IP address.
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…
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…
Cloudflare Error 1012: Access denied
The site owner blocked access with a rule that matched your request (often due to malicious activity detected from your IP).
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…
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.
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.
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…
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).
curl: (60) SSL certificate problem: unable to get local issuer certificate
curl could not verify the server's certificate — missing CA, incomplete chain, self-signed or expired certificate.
Two steps away (36)
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.
driver failed programming external connectivity on endpoint: iptables: No chain/target/match by that name
Docker’s iptables rules were wiped (firewalld/ufw reload, iptables flush) while Docker was running, so it can’t publish ports.
Error creating: pods is forbidden: violates PodSecurity "restricted:latest": allowPrivilegeEscalation != false ...
The namespace enforces a Pod Security Standard (baseline/restricted) and the pod spec breaks one of its rules.
WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! (ssh host key changed)
The server’s SSH host key differs from the one saved in ~/.ssh/known_hosts — usually because the server was rebuilt or the IP was…
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY
apt can’t verify a repository’s signature because the repo’s signing key isn’t installed (or has expired/rotated).
Azure SQL: Cannot open server 'x' requested by the login. Client with IP address 'y' is not allowed to access the server (Error 40615)
The Azure SQL server firewall doesn’t allow your client’s IP address.
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…
HTTP 429 Too Many Requests
You’ve hit a rate limit — too many requests in a given time window. Slow down and retry later.
Cloudflare Error 520: Web Server Returned an Unknown Error
Cloudflare connected to your origin, but the origin returned an empty, unknown or invalid response.
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.
Cloudflare Error 525: SSL Handshake Failed
Cloudflare couldn’t complete a TLS handshake with your origin (SSL mode Full / Full strict).
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.
fatal: unable to access 'https://…': SSL certificate problem: unable to get local issuer certificate
Git doesn’t trust the HTTPS server’s certificate — corporate proxy, self-hosted Git with an internal CA, or outdated CA bundle.
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).
Cloudflare Error 1009: Access denied — The owner of this website has banned the country or region your IP address is in
The site blocks visitors from your country/region.
Cloudflare Error 1010: The owner of this website has banned your access based on your browser's signature
Cloudflare’s bot detection blocked the request because its browser fingerprint looks automated.
Cloudflare Error 1011: Access denied (Hotlinking denied)
An image or file is being loaded from another site, and Cloudflare Hotlink Protection blocked it.
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.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
ssh: connect to host x port 22: Connection refused
The server answered, but nothing is listening on the SSH port — sshd isn’t running, it uses another port, or a firewall actively…
ssh: connect to host github.com port 22: Connection timed out
Outbound SSH on port 22 is blocked (firewall, corporate or public Wi-Fi).
kex_exchange_identification: Connection closed by remote host
The SSH connection was closed before the handshake — server overload, rate limiting, or a proxy/firewall interfering.
connect: Network is unreachable (ENETUNREACH)
The host has no route to the destination network — no default gateway, interface down, or trying IPv6 without IPv6 connectivity.
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.
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.
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…
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_DATE_INVALID (certificate expired)
The site’s certificate has expired (or isn’t valid yet) — or the device clock is wrong.
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.
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…
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.
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.
OpenSSL: error:num=20:unable to get local issuer certificate / SSL: CERTIFICATE_VERIFY_FAILED
The client could not build a chain from the server's certificate to a CA it trusts — the issuer is missing locally or the server…
Node/OpenSSL: Error: self signed certificate (code: DEPTH_ZERO_SELF_SIGNED_CERT)
The server presented a self-signed certificate (issuer equals subject), which no CA vouches for.
curl: (51) SSL: no alternative certificate subject name matches target host name 'example.com'
The certificate's names (SANs) don't include the host curl connected to.
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