First identify whether the failure follows one website, one browser, one device, or one network. That comparison prevents unnecessary resets.
Chrome reached the network, but the connection was closed before the page finished loading. A router, VPN, security filter, proxy, browser state, or the website itself can reset the session.
Chrome cannot validate the website certificate for the current connection. A wrong clock, expired certificate, captive portal, interception, or unsafe site configuration can trigger the warning.
The website is sending the browser through a redirect loop. Conflicting cookies, HTTP-to-HTTPS rules, login state, proxy settings, or the website configuration can cause the loop.
The DNS lookup did not return a usable address for the domain. The name may be mistyped, expired, temporarily unavailable, filtered, or failing through the current DNS resolver.
The destination was reached, but nothing accepted the connection on the requested service. The website may be down, blocked, misconfigured, or reachable only through a specific network.
The server understood the request but refuses to authorize it. Permissions, login state, region, IP reputation, security rules, or a private resource can produce HTTP 403.
The service is rate-limiting requests from the browser, account, app, or IP address. Repeated refreshes, automation, extensions, shared networks, or service limits can trigger HTTP 429.
A gateway or proxy received an invalid response from an upstream server. The website, hosting platform, CDN, load balancer, or origin service is usually responsible for HTTP 502.
The server is temporarily unable to handle the request. Maintenance, overload, failed dependencies, disabled application pools, or capacity limits commonly produce HTTP 503.
A gateway waited too long for an upstream service to respond. Slow database work, overloaded application servers, network faults, or timeout settings commonly cause HTTP 504.