Vercel access problemVercel preview link asks visitors to log in to Vercel

Why Vercel asks for a login, and the fix

1. 01

   Vercel Authentication protects the preview

   “Users attempting to access the deployment will encounter a Vercel login redirect.” Vercel, Vercel Authentication

   Only people with access to the project get through. For a client or tester without a Vercel account, share a Shareable Link for the deployment instead of the plain URL.

2. 02

   You shared a generated URL, not the production domain

   “Standard Protection is the recommended option for most projects. It protects all domains except production domains.” Vercel, Deployment Protection

   Standard Protection covers every URL except production domains, so a my-project-1234.vercel.app address can be protected while your own domain is public. Share the production domain for anything a customer should see.

3. 03

   A webhook or test hits a protected URL

   “Using a header is the recommended approach for most automation tools:” Vercel, Protection Bypass for Automation

   Stripe, Slack or a test run can’t log in. Create a Protection Bypass for Automation secret in the project settings and send it in the x-vercel-protection-bypass header, or as a query parameter where a service can’t set headers.

   x-vercel-protection-bypass: your-generated-secret

4. 04

   The app fetches its own VERCEL_URL

   “For client-side requests, use relative paths in the fetch call to target the current domain.” Vercel, Deployment Protection

   Server code that calls the app through VERCEL_URL gets the login page back once protection covers that URL. Use relative paths in the browser, and the incoming request’s origin and cookies on the server.

   // Before
   fetch(`${process.env.VERCEL_URL}/some/path`);
   
   // After
   fetch('/some/path');

Checked against the vendor’s docs on November 2, 2026: Vercel docs: Deployment Protection; Vercel docs: Vercel Authentication; Vercel docs: Protection Bypass for Automation.

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