Error map
ENOTFOUND Error: getaddrinfo ENOTFOUND host / Name or service not known
API · layer 4, Application & API
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…
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.
dial tcp: lookup registry-1.docker.io: no such host / Temporary failure in name resolution during docker build
DNS isn’t working for the Docker daemon or inside build containers, so pulls and package downloads fail.
java.net.ConnectException: Connection refused
Nothing is listening at the host:port the Java client connected to.
java.net.SocketException: Connection reset
The remote side closed the TCP connection abruptly while Java was reading or writing.
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.
cURL error 6: Could not resolve host: api.example.com
PHP cURL couldn’t resolve the hostname via DNS.
ConnectionRefusedError: [Errno 111] Connection refused
Nothing is listening on the host/port Python tried to connect to.
Site Health: The REST API encountered an error / Your site could not complete a loopback request (cURL error 28)
WordPress couldn’t call itself over HTTP — needed for the block editor, cron, plugin/theme editors and Site Health.
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.
fatal: unable to access 'https://github.com/…': Could not resolve host: github.com
DNS lookup for the Git host failed from this machine.
fatal: early EOF — fatal: index-pack failed
A clone or fetch was cut off mid-transfer.
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.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
Cloudflare Error 522: Connection Timed Out
Cloudflare’s TCP connection to your origin timed out — the origin didn’t answer at all.
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.
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…
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
npm ERR! code ELIFECYCLE / Command failed with exit code 1
An npm script (build, start, test, postinstall) exited with an error. ELIFECYCLE is only the wrapper — the real error is printed…
Cloudflare Error 521: Web Server Is Down
Cloudflare couldn’t connect to your origin — the connection was refused.
java.net.UnknownHostException: api.example.com
DNS resolution failed for 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.
TypeError: Failed to execute 'json' on 'Response': body stream already read
A fetch Response body was consumed twice (e.g. calling .text() then .json()).
TypeError: fetch failed (cause: ConnectTimeoutError / ECONNREFUSED / UND_ERR)
Node’s built-in fetch (undici) couldn’t complete the request; the real reason is in error.cause.
cURL error 35: OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to host:443
The TLS handshake failed — protocol/cipher mismatch, a proxy interfering, or the server closed the connection.
error: RPC failed; HTTP 400 curl 22 / curl 92 HTTP/2 stream was not closed cleanly — the remote end hung up unexpectedly
A large HTTPS push/clone broke mid-transfer — size limits, proxies or flaky HTTP/2.
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.
cURL error 28: Operation timed out after 30001 milliseconds with 0 bytes received
A PHP cURL (or Guzzle) request timed out before the remote server answered.
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.
DNS not working inside a Kubernetes pod (could not resolve host / nslookup: can't resolve)
Pods can’t resolve service names or external hosts — CoreDNS is down, blocked by NetworkPolicy, or the upstream resolver fails.
TypeError: f() takes 1 positional argument but 2 were given
A function was called with more positional arguments than it accepts — very often a method missing `self`.
TypeError: f() missing 1 required positional argument: 'x'
A function was called without a required parameter.
IndexError: list index out of range
Code accessed a list position that doesn’t exist.
WordPress: Updating failed. The response is not a valid JSON response.
The block editor saved via the REST API but got HTML or an error page back — broken permalinks, a security plugin/WAF, or PHP out…
net::ERR_BLOCKED_BY_CLIENT
A browser extension (ad blocker, privacy tool) blocked the request.
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.
MySQL ERROR 2002 (HY000): Can't connect to local MySQL server through socket
The client couldn’t reach the MySQL server — it isn’t running, or the client is looking for the socket/port in the wrong place.
Docker: Bind for 0.0.0.0:80 failed: port is already allocated
Another container or host process already publishes that host port.
Linux: Permission denied
Your user (or the service user) lacks read/write/execute permission on a file, directory or one of its parents.
fatal: No url found for submodule path 'x' in .gitmodules
A submodule entry exists in the index but its URL is missing from .gitmodules.
Error [ERR_STREAM_PREMATURE_CLOSE]: Premature close
A stream ended or was destroyed before it finished — often a client disconnect or upstream aborting a download.
npm ERR! code ENOTFOUND — request to https://registry.npmjs.org/x failed, reason: getaddrinfo ENOTFOUND registry.npmjs.org
npm couldn’t resolve the registry hostname.
Get "https://registry-1.docker.io/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded)
Docker couldn’t reach the registry in time — a network, DNS, proxy or firewall problem between your machine and the registry.
HTTP 511 Network Authentication Required
A captive portal (hotel, airport, office Wi-Fi) is intercepting your traffic until you log in or accept its terms.
Windows Update error 0x8024402C (cannot connect to update server)
Windows Update can’t reach Microsoft’s servers — a proxy, DNS, firewall or WSUS setting is blocking the connection.
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