deployment_not_found: Vercel 404 NOT_FOUND, no deployment attached to that hostname

TL;DR

deploymentnotfound on Vercel means no deployment is attached to the hostname you opened: the error page shows 404 NOTFOUND with Code DEPLOYMENTNOT_FOUND. The domain was never assigned to the project, the deployment behind the URL was deleted, or the URL is a stale preview link. Fix it by attaching the domain in the project under Settings, Domains, or by promoting a Ready build to Production; redeploying alone does not attach a domain.

404: NOT_FOUND
Code: DEPLOYMENT_NOT_FOUND

Use this when

• A Vercel URL shows 404 NOTFOUND and the code line reads DEPLOYMENTNOT_FOUND
• A custom domain was bought and DNS points at Vercel, but the site never loads
• An old preview or deployment URL that used to work now returns 404

Not for this skill when

• The code is NOTFOUND without DEPLOYMENT in front of it: a deployment is serving but its routes have no match, which is a routing or output problem
• Your own app renders its 404 page: that is your code answering, not Vercel
• The deploy itself failed in the build log: fix the build first, then come back here if the hostname still 404s

Steps

1. Read the code, not just the 404. Open the failing URL and confirm the page shows DEPLOYMENTNOTFOUND, not plain NOT_FOUND.

Expected: you have confirmed which of the two Vercel 404s this is before changing anything.

2. Attach the domain to the project. In the Vercel dashboard open your project, then Settings, then Domains, type the domain and click Add. It takes effect within seconds and does not need a redeploy.

Expected: refreshing the URL loads your site instead of the error page.

3. Check you are opening the right URL. Preview URLs (project-git-branch-team.vercel.app) are ephemeral and die when the branch or project is deleted. Use the production domain, or click Visit on the latest deployment.

Expected: the production URL works even if the bookmarked preview URL does not.

4. Confirm a Ready production deployment exists. Open the Deployments tab. If the latest Production deployment shows Error or Canceled there is nothing to serve; fix the build and redeploy. If a good build exists but is not Production, promote it.

Expected: the Deployments tab shows a Ready build marked Production.

5. If the domain shows as assigned but the error persists, check whose project it is assigned to. A domain can only serve one project; assigned to a different project or team in the same account, it 404s on yours.

Expected: the domain sits on the project you are testing, in the team you are testing.

Variant phrasings

404 notfound code deploymentnot_found

The full error page text as one search string. Same diagnosis and same fix: attach the domain (step 2) or promote a Ready build (step 4).

deployment not found vercel

The plain-words version of the same failure. If Vercel answered the request, the code on the page is DEPLOYMENTNOTFOUND even when the person searching does not quote it.

vercel domain 404 after adding custom domain

Adding DNS records is only half of the setup: until the domain is also added under Settings, Domains on the project, Vercel has nowhere to route it and returns this code.

Root cause

Vercel routes each hostname to one specific deployment. If the domain was never added to the project, was removed, or the deployment the URL pointed at was deleted, the edge has nowhere to send the request and returns DEPLOYMENTNOTFOUND. Redeploying does not attach a domain, which is why people get stuck in a redeploy loop.

Edge cases

• Domain assigned but still 404ing: DNS may still be propagating (up to 24 hours), or the domain is assigned to a different project or team.
• Deployment Protection is on: deployment URLs ask for a Vercel login by design. That is not this error; use the production domain instead.
• The default project.vercel.app name is taken by someone else: pick another project name so the default slug is free.

Tool compatibility

Vercel, all plans (Hobby, Pro, Enterprise), for both vercel.app domains and custom domains. Dashboard steps are the same on every plan.

Related skills

• Vercel Blob client upload: Access denied, provide a valid token - a different Vercel failure, after the deployment itself loads: https://vectle.com/skills/sklk8NXBSuuEqWele64_QODA
• Diagnose timeouts for AI routes deployed on Vercel: https://vectle.com/skills/skl_jxLAo75dHb9lR1SE4WsruQ

Provenance

Built from real deployment writeups documenting this exact failure, linked in the evidence.

Multiple real deployment writeups document this exact failure. One project manual records the troubleshooting entry verbatim: Error: 404: NOT_FOUND Code: DEPLOYMENT_NOT_FOUND, with the diagnosis that DNS is pointing at Vercel fine but Vercel does not know which project to display, and the verified fix: go to the Vercel Dashboard, open the project, Settings -> Domains, type the domain and click Add, then refresh. A second writeup adds the key distinction: read the code on the 404 page, because NOTFOUND means a deployment is serving but the route has no match, while DEPLOYMENTNOTFOUND means no deployment is attached to the hostname at all, fixed by attaching the domain or promoting the right build to Production. Full threads: https://github.com/bgillis99-pixel/final-125111am/blob/HEAD/DEPLOYMENTMANUAL.md and https://github.com/sakshamfit/restaurant/blob/HEAD/DEPLOY.md