Error map
ConnectException java.net.ConnectException: Connection refused
Java · 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…
Cloudflare Error 522: Connection Timed Out
Cloudflare’s TCP connection to your origin timed out — the origin didn’t answer at all.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
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.
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.
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.
0x80070035: The network path was not found (System error 53)
Windows can’t reach the shared folder — name resolution, SMB settings, firewall or network discovery is preventing it.
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.
WordPress: Download failed. A valid URL was not provided / cURL error 60 / Could not resolve host: downloads.wordpress.org
WordPress couldn’t download an update package — outbound HTTP blocked, DNS failure, SSL CA issues, or a premium plugin license UR…
Cloudflare Error 521: Web Server Is Down
Cloudflare couldn’t connect to your origin — the connection was refused.
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.
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.
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 520: Web Server Returned an Unknown Error
Cloudflare connected to your origin, but the origin returned an empty, unknown or invalid response.
Cloudflare Error 524: A Timeout Occurred
Cloudflare connected to the origin, but the origin didn’t send an HTTP response within 100 seconds.
HTTP 502 Bad Gateway
A proxy or gateway (Nginx, load balancer, CDN) got an invalid response — or no response — from the upstream server behind it.
Too many open files (EMFILE)
The process hit its file-descriptor limit — sockets, files and pipes all count.
fatal: unable to access 'https://github.com/…': Could not resolve host: github.com
DNS lookup for the Git host failed from this machine.
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.
AWS Lambda: Task timed out after X seconds
The function ran longer than its configured timeout (default 3 seconds) and Lambda stopped it.
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.
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…
Mixed Content: The page was loaded over HTTPS, but requested an insecure resource
An HTTPS page tried to load a script, API or image over plain HTTP, and the browser blocked (or warned about) it.
CLEARTEXT communication to host not permitted by network security policy
Android 9+ blocks plain `http://` requests by default; the app tried to call a non-HTTPS URL.
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…
gyp ERR! build error / node-gyp rebuild failed
A dependency with native C/C++ code couldn’t compile — missing build tools, Python, or an unsupported Node version.
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.
Windows Error 0x80070005 (E_ACCESSDENIED): Access is denied
Windows refused an operation because the account or process lacks permission — seen in Windows Update, installers, Task Scheduler…
ssh: connect to host github.com port 22: Connection timed out
Outbound SSH on port 22 is blocked (firewall, corporate or public Wi-Fi).
fatal: early EOF — fatal: index-pack failed
A clone or fetch was cut off mid-transfer.
java.net.UnknownHostException: api.example.com
DNS resolution failed for the hostname.
java.net.SocketException: Connection reset
The remote side closed the TCP connection abruptly while Java was reading or writing.
QuotaExceededError: Failed to execute 'setItem' on 'Storage': Setting the value exceeded the quota
localStorage/sessionStorage is full (about 5 MB per origin) or storage is disabled.
WordPress: Briefly unavailable for scheduled maintenance. Check back in a minute.
An update was interrupted and WordPress left its `.maintenance` file behind, so the site stays in maintenance mode.
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.
Cloudflare Error 525: SSL Handshake Failed
Cloudflare couldn’t complete a TLS handshake with your origin (SSL mode Full / Full strict).
ConnectionRefusedError: [Errno 111] Connection refused
Nothing is listening on the host/port Python tried to connect to.
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…
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_ABORTED 404 (Not Found)
The browser cancelled the request — often because it returned an error (404) or the page navigated away.
AbortError: The user aborted a request. / signal is aborted without reason
A fetch was cancelled through an AbortController (or the browser cancelled it).
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.
net::ERR_NAME_NOT_RESOLVED (This site can't be reached — server IP address could not be found)
DNS couldn’t resolve the hostname in the browser.
WebSocket connection to 'wss://x' failed
The browser couldn’t open (or keep) a WebSocket connection.
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