Error map
MongoDB Atlas: connection timed out — IP not whitelisted MongoServerSelectionError: Could not connect to any servers in your MongoDB Atlas cluster. One common reason is that you're trying to access the database from an IP that isn't whitelisted
MongoDB · layer 5, Data
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)
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.
MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017
The MongoDB driver couldn’t find a reachable server for the connection string.
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.
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.
ConnectionRefusedError: [Errno 111] Connection refused
Nothing is listening on the host/port Python tried to connect to.
requests.exceptions.ConnectionError: HTTPSConnectionPool(host=…, port=443): Max retries exceeded with url
requests couldn’t connect — the inner error (NewConnectionError, NameResolutionError, SSLError, ConnectTimeout) says why.
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…
ping: google.com: Temporary failure in name resolution
The Linux host can’t resolve domain names — no working DNS server is configured or reachable.
client_loop: send disconnect: Broken pipe (SSH session drops when idle)
The SSH connection was cut — usually an idle timeout on a NAT router, firewall or the server, sometimes a network change.
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.
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.
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 408 Request Timeout
The server closed the connection because the client took too long to send the complete request.
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…
MongooseError: Operation `users.find()` buffering timed out after 10000ms
Mongoose queued a query waiting for a connection that never opened.
CastError: Cast to ObjectId failed for value "x" (type string) at path "_id"
A value that isn’t a valid 24-hex-character ObjectId was used in an _id query.
MongoServerError: E11000 duplicate key error collection: db.users index: email_1 dup key
An insert/update violated a unique index in MongoDB.
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.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
Error: getaddrinfo ENOTFOUND host / Name or service not known
DNS lookup for the hostname failed — the name is wrong, doesn’t exist, or this machine can’t resolve it.
HTTP 407 Proxy Authentication Required
A proxy between you and the server requires credentials before it will forward your request.
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.
fatal: early EOF — fatal: index-pack failed
A clone or fetch was cut off mid-transfer.
Cloudflare Error 521: Web Server Is Down
Cloudflare couldn’t connect to your origin — the connection was refused.
java.net.ConnectException: Connection refused
Nothing is listening at the host:port the Java client connected to.
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`.
fatal: unable to access 'https://github.com/…': Could not resolve host: github.com
DNS lookup for the Git host failed from this machine.
java.net.SocketException: Connection reset
The remote side closed the TCP connection abruptly while Java was reading or writing.
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.
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.
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…
java.net.UnknownHostException: api.example.com
DNS resolution failed for the hostname.
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.
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.
Received disconnect: Too many authentication failures
Your SSH agent offered too many keys before the right one, and the server cut the connection (MaxAuthTries, default 6).
WARNING: UNPROTECTED PRIVATE KEY FILE! Permissions 0644 for 'key.pem' are too open
SSH refuses to use a private key that other users can read; it must be readable only by you (chmod 600).
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 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…
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.
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.
perl: warning: Setting locale failed / bash: warning: setlocale: LC_ALL: cannot change locale
Your session asks for a locale (often forwarded by SSH from your Mac/PC) that isn’t generated on the server.
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.
[!] CDN: trunk URL couldn't be downloaded: https://cdn.cocoapods.org/...
CocoaPods couldn’t reach its CDN spec repo — network/proxy issues, rate limiting, or an outdated CocoaPods.
java.io.IOException: Stream closed
Code read or wrote a stream after it was closed — often by a try-with-resources block or a wrapper closing the underlying stream.
Error: write EPIPE
Node wrote to a pipe or socket whose other end was already closed.
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.
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