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Troubleshooting38 guides12 languages

Fix Browser, DNS and HTTP Errors

What each error means and how to fix it, step by step: DNS_PROBE_FINISHED_NXDOMAIN, ERR_CONNECTION_REFUSED, 403 Forbidden, 502 Bad Gateway, SSL errors and more, each with a free tool to confirm the fix.

Most read in Troubleshooting

  1. 01ERR_QUIC_PROTOCOL_ERROR: Meaning & Fix in Chrome and EdgeTroubleshooting8 min read
  2. 02ERR_SSL_PROTOCOL_ERROR: Fix It in Chrome, Edge & LocalhostTroubleshooting11 min read
  3. 03DNS_PROBE_STARTED: Meaning & Fix on Chrome, Android, WindowsTroubleshooting8 min read

All 38 troubleshooting guides

Grouped by what your screen says. A date marks guides re-tested in the last 30 days.

Chrome & Edge errors16

ERR_ADDRESS_UNREACHABLE Fix for Router, Mac & AndroidOct 2711 minERR_CACHE_MISS Fix It in Chrome, Edge, Android & WebViewOct 269 minERR_CERT_AUTHORITY_INVALID Fix in Chrome, Edge & AndroidOct 269 minERR_CONNECTION_CLOSED What It Means & How to Fix ItOct 2710 minERR_CONNECTION_REFUSED Meaning & Fix (Chrome, All Browsers)Oct 2611 minERR_CONNECTION_RESET What It Means & How to Fix ItOct 2711 minERR_CONNECTION_TIMED_OUT & ERR_TIMED_OUT: Causes and FixesOct 2711 minERR_EMPTY_RESPONSE What It Means & How to Fix ItOct 2711 minERR_HTTP2_PROTOCOL_ERROR Meaning & Fix in Chrome and EdgeOct 2711 minERR_NAME_NOT_RESOLVED (-105): Meaning & Fix in ChromeOct 268 minERR_NETWORK_CHANGED What It Means & How to Fix ItOct 2710 minERR_QUIC_PROTOCOL_ERROR Meaning & Fix in Chrome and EdgeOct 268 minERR_SSL_PROTOCOL_ERROR Fix It in Chrome, Edge & LocalhostOct 2611 minERR_SSL_VERSION_OR_CIPHER_MISMATCH Fix in Chrome & EdgeOct 277 minERR_TOO_MANY_REDIRECTS How to Fix It (All Browsers)Oct 2611 minERR_TUNNEL_CONNECTION_FAILED What It Means & How to Fix ItOct 279 min

HTTP status codes10

400 Bad Request: What It Means & How to Fix ItOct 2710 min401 Unauthorized & 401 Authorization Required: How to FixOct 2713 min403 Forbidden Error: What It Means & How to Fix ItOct 2612 min405 Method Not Allowed: What It Means & How to Fix ItOct 278 minHTTP Error 429 Too Many Requests: Meaning & FixOct 2610 minHTTP 500 Internal Server Error: Causes & Fix (nginx, Apache)Oct 2711 min502 Bad Gateway: What It Means & How to Fix ItOct 2712 min503 Service Unavailable: What It Means & How to Fix ItOct 269 min504 Gateway Time-out: What It Means & How to Fix ItOct 2710 minCloudflare Error 520: What It Means & How to Fix ItOct 2710 min

DNS & connection8

DNS_PROBE_FINISHED_NXDOMAIN What It Means & How to Fix ItOct 2610 minDNS_PROBE_STARTED Meaning & Fix on Chrome, Android, WindowsOct 268 min"This Network Is Blocking Encrypted DNS Traffic" FixOct 2610 minDNS Server Unavailable: What It Means & How to Fix ItOct 279 minHow to Fix DNS Server Not Responding (Step-by-Step)Oct 278 minHow to Fix Slow DNS Lookup in Chrome, Windows & MacOct 279 minHow to Flush DNS: Windows, Mac, Linux, Fedora & ChromeOct 268 minWiFi Connected But No Internet? 10 Fixes That WorkOct 2710 min

Certificates, Firefox & other4

Connection Is Not Private Fix It on iPhone, iPad & ChromeOct 2611 minPR_CONNECT_RESET_ERROR in Firefox: Causes & How to Fix ItOct 279 minX-Frame-Options Fix “Refused to Connect” in an iframeOct 2712 minHow to Test a Public API Endpoint: DNS, TLS, Headers & CORSOct 2710 min

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About the author

Shaik Vahid Founder of DNS Robot

Vahid spent years in web hosting support fixing domains, DNS records, SSL certificates and email delivery for customers. He builds DNS Robot's tools and writes these guides from the errors people actually hit.