Error guide / DNS_PROBE_FINISHED_BAD_CONFIG

DNS_PROBE_FINISHED_BAD_CONFIG error

DNS_PROBE_FINISHED_BAD_CONFIG is Chrome's verdict after a failed name lookup: the browser retried the query with its own DNS probe, and the probe concluded that the resolver in use is not working the way it should. Unlike NXDOMAIN, which means the name definitely does not exist, BAD_CONFIG means the lookup never completed cleanly, so nothing was actually learned about the domain. Visitors usually see it on one machine or one network while the same site opens fine elsewhere. Site owners see it reported from every network when the domain's own name servers are the ones failing.

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What causes it

In most cases the fault is local: the computer or router points at a DNS server that is unreachable or answers with garbage, a stale cache is stuck, or a VPN, DNS-filtering app or security suite is intercepting queries. A router that hands out its own address as the resolver while its upstream forwarder is dead produces this error reliably. Less often the domain is genuinely broken: its name servers are unreachable, the delegation is lame (the NS records at the registry point at servers that do not answer for that zone), or the zone exists but has no usable records. Both sides produce the identical Chrome screen, which is why guessing which one it is wastes time.

How to fix it

  1. Run the domain through the DNS check below first, because it queries authoritative name servers from our server, not from your machine. If it returns A, NS and SOA records normally, the domain's DNS is healthy and the fault is on your side, so work through the local steps. If NS or SOA come back empty or with an error, the zone itself is broken and no local fix will help. If the check instead reports that the name does not exist, you are looking at NXDOMAIN, which is a different case.
  2. If the check came back clean, replace your resolver with a public one: set 1.1.1.1 or 8.8.8.8 in the IPv4 and IPv6 settings of the network adapter, then reload the page. This alone clears most BAD_CONFIG cases, because it bypasses whatever address the router or ISP handed you.
  3. Flush the stale entries: run ipconfig /flushdns on Windows, or sudo dscacheutil -flushcache and sudo killall -HUP mDNSResponder on macOS. Then clear Chrome's own cache at chrome://net-internals/#dns and its sockets at chrome://net-internals/#sockets.
  4. Disable VPN, proxy, DNS-filtering tools and the web-protection module of your antivirus one at a time. Software that reroutes DNS is a frequent cause, and a removed VPN can leave a dead resolver address behind in the adapter settings.
  5. Power-cycle the router, and if the error follows you across several devices on the same Wi-Fi, check its DHCP settings for a DNS server address that no longer works. Open the same site over mobile data as a control: if it loads there, the problem is your network, not the domain.
  6. If the check showed the domain's DNS broken and you manage it, confirm at the registrar that the NS records match the name servers your DNS provider actually serves the zone from, that the zone still exists on every one of them, and that an A or AAAA record is present. NS records pointing at servers that no longer host the zone is the classic lame delegation and needs a fix on the registrar side, not on the web server.

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