Why Vercel custom domains return ERR_CONNECTION_CLOSED on trailing dot FQDN

Help
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1

Domain

deckclip.app (production custom domain on Vercel)

Problem

Visiting https://deckclip.app./ (FQDN with a trailing dot) fails in Chrome with ERR_CONNECTION_CLOSED — the connection drops before any HTTP response. https://deckclip.app (no trailing dot) works normally.

Current vs Expected Behavior

  • Current: TLS does not complete when the client uses the trailing-dot form; browser shows connection closed.
  • Expected: Edge should treat deckclip.app. the same as deckclip.app for TLS SNI / host matching (normalize by stripping a trailing dot), similar to large public sites, then serve or redirect as usual.

Why Configuration Doesn’t Fix It

This fails at TLS, so vercel.json redirects never run.

Steps to Reproduce

Browser: Open https://deckclip.app./ → ERR_CONNECTION_CLOSED.

CLI (openssl):

# Trailing dot in SNI — fails / no cert
echo | openssl s_client -connect deckclip.app:443 -servername 'deckclip.app.'

# No trailing dot — succeeds
echo | openssl s_client -connect deckclip.app:443 -servername 'deckclip.app'

Project Details

Static site on Vercel (Next.js static export). Framework details are secondary; the issue reproduces purely at TLS/SNI against the custom domain.

Request

Can Vercel normalize trailing-dot FQDN hostnames at the edge for SNI and routing?

Thanks.

2

The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.

You can also use v0 to narrow down the possibilities.