Guide
Supabase project URL shows DNS_PROBE_FINISHED_NXDOMAIN for my customers
A customer opens your app and the browser reports DNS_PROBE_FINISHED_NXDOMAIN for your Supabase project hostname. This applies to apps made with AI app builders that use Supabase as their backend.
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Why it happens
An NXDOMAIN error means DNS resolution failed for the hostname being connected to: the hostname does not exist, or it cannot resolve on the network the connection comes from. Supabase project hostnames end in .supabase.co, while .supabase.com serves the marketing site and dashboard, not project connections.
Possible causes
- The project reference in the hostname has a single mismatched character, which produces NXDOMAIN.
- The hostname ends in .supabase.com instead of .supabase.co; project hostnames never end in .supabase.com.
- The project is paused, so it stops serving its hostname and connections resolve as NXDOMAIN even though the project still exists.
- The project was deleted, and a deleted project's hostname stops resolving permanently.
- The network the customer is on has a DNS resolver that fails to resolve supabase.co and unrelated *.supabase.co hostnames, while a VPN or another network resolves them. This is common on restrictive mobile carrier, office or ISP networks.
- An anti-virus, network or firewall system on the customer's side is blocking access.
- The app uses a custom domain, whose DNS records are managed by your own domain registrar or DNS provider, not Supabase, and that hostname fails to resolve.
You can't see it yourself
You're signed in, your customers aren't. Your own account already exists and is allowed in, and your own browser, preview or device is not a new customer's network. A resolver problem on a customer's carrier or office network, or a hostname that never resolves for them, does not show up from where you are testing.
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Related: v0 with Supabase: sign-in sends people to the wrong URL · It works in the preview but breaks after I deploy · My builder says the app is tested, but my customers hit problems
Sources
VibeFix's check can show this on your live app: its AI agent signs up to your app like a new person, uses it on a phone and a computer, and shows what breaks. VibeFix checks; it does not fix your app.
Last checked: 21 October 2026, against the sources listed above.
VibeFix is independent. Lovable, Bolt, Replit, Base44, v0 and Supabase are trademarks of their owners.
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