Your site loads for you, but the uptime monitor reports failures because it gets a Vercel login redirect instead of your page. Two causes are common: a Deployment Protection scope that covers the URL being checked, or a monitor that requests a URL that is not a production domain.
With All Deployments selected, Vercel protects both preview and production URLs, including your production domain. Vercel Authentication redirects anonymous visitors and monitoring probes to a Vercel login before your code runs.
How to tell: An anonymous request to your production domain gets the Vercel login redirect, and the project's Deployment Protection scope reads All Deployments.
Standard Protection protects every domain except production domains, so a hostname that is not assigned as a production domain stays behind the login. Your DNS records can be correct while the hostname sits on a different environment. The domain docs treat DNS setup and environment assignment as separate steps.
How to tell: Your apex or main production domain loads publicly, but the new subdomain redirects to login even though its DNS records are configured.
With Standard Protection enabled, the production generated deployment URL is restricted, even though your custom production domain is public. A monitor configured with a vercel.app address sees the login redirect.
How to tell: The same page returns normally on your custom production domain, but the generated vercel.app URL redirects to login.
Run an anonymous request against the exact URL your monitor uses and read the response. A redirect to Vercel login means Deployment Protection is answering before your code runs.
curl -sI https://status.example.com/Open the project's Settings, then Deployment Protection, and check whether the scope is All Deployments. If the production site should be public, choose Standard Protection, which protects all domains except production domains.
Open the project's Settings, click the Environments menu item, and select the environment you want the domain assigned to. For a public site, that is Production. Adding DNS records is a separate step after the domain is added, so correct DNS does not tell you which environment serves the hostname.
Replace any generated vercel.app address in the uptime check with your custom production domain. Under Standard Protection the production generated deployment URL is restricted, so a public check against it fails.
If the checked URL must stay protected, create a secret under Protection Bypass for Automation and send it in the x-vercel-protection-bypass header. If the monitor cannot set headers, send the same name as a query parameter. Redeploy after you regenerate or replace the secret, because deployments carry the value from build time.
curl -sI -H "x-vercel-protection-bypass: $BYPASS_SECRET" https://status.example.com/Quick check: curl -sI https://your-domain/ | head -5 # a redirect to Vercel login means Deployment Protection is answering
2 of the 937 verified cases from the last 12 months in our data match this symptom (0.2%). How we collect and verify cases.
On Gemmein the Development site (https://<slug>-dev.gemmein.dev) is a private preview, while the public Live site is a separate address (https://<slug>.gemmein.dev) that changes only when you approve putting a version live. Your own domain can show the Live site but never the private preview.
Vercel Authentication redirects visitors to a Vercel login when it protects the URL they request. Team members, project members, granted users, shareable-link holders and callers using the bypass header can get through.
No. Standard Protection protects all domains except production domains, while All Deployments protects preview and production URLs, including the production domain. A hostname that is not a production domain is protected under Standard Protection.
Yes. The docs describe Protection Bypass for Automation for monitoring tools. Send the secret in the x-vercel-protection-bypass header, or as a query parameter if the tool cannot set headers.
The docs list Protection Bypass for Automation as available on all plans, which includes Hobby.
Every cause and step above was checked against these pages on 3 Nov 2026.
This is one symptom of a wider failure pattern: Health checks pass but production is failing silently. The guide covers every cause we see for it, on any stack.