ERR_PROXY_CONNECTION_FAILED: 8 ways to fix it

ERR_PROXY_CONNECTION_FAILED is Chrome saying it was told to use a proxy but could not establish a connection to it. Crucially, the failure is between you and the proxy, not between the proxy and the website — so the fix is almost always in your proxy configuration, not the site you were trying to reach. The usual causes are a mistyped host or port, a proxy that is offline or expired, a stale system-wide proxy setting left behind by another app, or a browser extension quietly overriding your settings.

Because Chrome uses the operating system's proxy settings by default, this error frequently outlives the app that caused it — a VPN or proxy tool that crashed can leave a dead proxy configured system-wide, and every Chrome request then fails. The eight fixes below move from the most common (wrong address, dead proxy) to the more obscure (extensions, LAN settings, DNS). For a valid endpoint to test against, s4m proxies live at proxy.s4m.online — SOCKS5 on 1080, HTTP on 3128, with USER:PASS. See the proxy page and the related 407 guide.

Most repeat occurrences trace back to flaky or free proxies and to apps that do not clean up their system proxy on exit. Two habits prevent the majority: test any new proxy with a one-line curl before pointing a browser at it, and prefer a proxy tool or endpoint that stays up rather than free-list entries that expire mid-session. If you must use the free public proxy list, treat every entry as disposable and expect this error often.

Honestly, a stable connection is what you are really buying with a paid proxy: s4m runs authenticated datacenter SOCKS5 and HTTP endpoints on managed infrastructure, metered pay-as-you-go, so the endpoint is there when Chrome asks for it. That does not make datacenter IPs invisible to anti-bot systems — it just removes the "the proxy went away" class of failure. When you need a single stable, allowlistable exit, add a dedicated personal IP. Validate any endpoint quickly with the tools, and if the error turns out to be an auth challenge, read the 407 guide.