🌐 Networking Errors

45 error notes

Access to XMLHttpRequest at '...' from origin '...' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

corsaxiospreflighthttp-options

networkingintermediate

Fixing MaxRetryError and Connection Refused in Python urllib3

urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='...', port=80): Max retries exceeded with url: /api/endpoint (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object>: Failed to establish a new connection: [Errno 111] Connection refused'))

pythonrequestsurllib3networking

networkingintermediate

Fixing requests.exceptions.ReadTimeout in Python: Stop Your Scripts from Hanging

requests.exceptions.ReadTimeout: HTTPSConnectionPool(host='api.example.com', port=443): Read timed out. (read timeout=30)

pythonrequeststimeoutapi-integration

networkingintermediate

Fix "Permission denied (publickey)" When Connecting via SSH

Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).

sshlinuxdevopssecurity

networkingbeginner

Fixing the ERR_NETWORK_CHANGED Error: 5 Ways to Stabilize Your Connection

ERR_NETWORK_CHANGED

browsernetworkchromedns

networkingintermediate

Fix DEPTH_ZERO_SELF_SIGNED_CERT Error in Node.js When Calling Internal HTTPS APIs

Error: self signed certificate (code: 'DEPTH_ZERO_SELF_SIGNED_CERT')

nodejshttpssslcertificate

networkingintermediate

Fix Nginx "upstream sent too big header" 502 Bad Gateway Error

502 Bad Gateway - [error] upstream sent too big header while reading response header from upstream

nginxnetworkingproxybackend

networkingintermediate

Fixing 'Error: connect EADDRNOTAVAIL' – How to Solve Ephemeral Port Exhaustion on Linux

Error: connect EADDRNOTAVAIL

networkingtcplinux-performancedevops

networkingintermediate

Fixing Nginx WebSocket 400 Errors: A Practical Reverse Proxy Guide

WebSocket connection to 'wss://example.com/ws' failed: Error during WebSocket handshake: Unexpected response code: 400

websocketnginxproxywss

networkingintermediate

Fixing 504 Gateway Time-out: How to Resolve Nginx Upstream Timeouts

504 Gateway Time-out

nginxgateway-timeoutnetworkingproxy

networkingbeginner

Fixing Error: listen EADDRINUSE (Port Already in Use)

Error: listen EADDRINUSE: address already in use :::8080

networkingweb-developmentnode-jsdevops

networkingintermediate

How to Fix the ERR_TOO_MANY_REDIRECTS Error (and Why It Happens)

ERR_TOO_MANY_REDIRECTS

networkinghttptroubleshootingweb-development

networkingintermediate

Fixing 'Error: read ECONNRESET' in Node.js - Troubleshooting Abrupt Connection Resets

Error: read ECONNRESET

nodejseconnresethttptcp

networkingintermediate

Fix NET::ERR_CERT_DATE_INVALID: Why Let’s Encrypt Failed to Auto-Renew

NET::ERR_CERT_DATE_INVALID

sslletsencryptcertbotnginx

networkingintermediate

Fix net::ERR_HTTP2_PROTOCOL_ERROR - Troubleshooting Browser Resource Loading

net::ERR_HTTP2_PROTOCOL_ERROR

http2networkingbrowsernginx

networkingintermediate

Fixing ERR_SSL_VERSION_OR_CIPHER_MISMATCH: Solving SSL/TLS Incompatibility

ERR_SSL_VERSION_OR_CIPHER_MISMATCH

ssltlshttpsnetworking

networkingbeginner

Fixing the 'Temporary failure in name resolution' Error on Linux

Temporary failure in name resolution

dnsresolv.conflinuxnetworking

networkingintermediate

Fixing Node.js 'getaddrinfo ENOTFOUND' Errors: A Practical Guide

Error: getaddrinfo ENOTFOUND api.example.com

nodejsdnsnetworkinggetaddrinfo

networkingintermediate

Fixing 'Error: socket hang up' in Node.js HTTP/HTTPS Requests

Error: socket hang up

nodejshttpsocketnetworking

networkingbeginner

Fix curl: (6) Could not resolve host When Calling APIs from Terminal or Scripts

curl: (6) Could not resolve host: api.example.com

curldnslinuxnetworking

networkingintermediate

Fix 502 Bad Gateway: When Your Proxy Can't Get a Valid Response

502 Bad Gateway

networkinghttpnginxgateway

networkingbeginner

Fixing Nginx SSL_ERROR_RX_RECORD_TOO_LONG: The Complete Guide

SSL_ERROR_RX_RECORD_TOO_LONG

sslnginxhttpsport

networkingintermediate

Fixing the 'connect: Network is unreachable' Error on Linux

connect: Network is unreachable

networkinglinuxgatewayrouting

networkingintermediate

Solving MTU Mismatch: Fixing the 'Frag needed and DF set' Error

Frag needed and DF set (mtu = 1500)

networkingmtufragmentationpacket-loss

networkingintermediate

Fix "connect ECONNREFUSED 127.0.0.1:5432" — Server or Database Connection Refused

Error: connect ECONNREFUSED 127.0.0.1:5432

networkingeconnrefusedbackenddatabase

networkingintermediate

How to Fix the [SSL: CERTIFICATE_VERIFY_FAILED] Error in Python

[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate

sslpythonapinetworking

networkingbeginner

Fixing net::ERR_PROXY_CONNECTION_FAILED in Chrome and Other Browsers

net::ERR_PROXY_CONNECTION_FAILED

networkingproxybrowser-errorchrome

networkingintermediate

Fix "Too many open files" (EMFILE) Error on High-Traffic Servers

Error: accept(2) failed: Too many open files (EMFILE)

linuxnetworkingulimitsocket

networkingintermediate

Fixing the 'No Access-Control-Allow-Origin' Header Error: A Practical Guide

Access to fetch at 'http://api.domain.com' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

corsweb-securityjavascriptbackend

networkingbeginner

Fixing SSH Error: Host key verification failed - Remote Host Identification Has Changed

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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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Host key verification failed.

sshlinuxsysadminsecurity

networkingintermediate