If Vercel deploy fails for no obvious reason, check for uppercase in the folder name

Scaffolding a Next.js project can hit a wall where nothing looks misconfigured, yet both scaffolding and deploy fail.

Symptom

#

The working directory was named CTI. Scaffolding and deploying straight from there:

cd /Users/mac/ws/claude/CTI
npx create-next-app@latest .     # fails name validation
vercel deploy                    # also fails name validation

Cause

#

Neither create-next-app nor Vercel allow uppercase characters in a project/app name. Both tools tried to reuse the directory name as the project name and rejected it at validation.

Fix

#

Rather than renaming the directory (it was already in use for other things and renaming wasn’t desirable), the project was scaffolded with a lowercase name in a temp location, then moved into the original directory — and the deploy target was linked explicitly with a lowercase project name via vercel link.

# 1. Scaffold with a lowercase name in a temp location
npx create-next-app@latest /tmp/cti-sentinel

# 2. Move the generated files into the original uppercase directory
mv /tmp/cti-sentinel/* /Users/mac/ws/claude/CTI/

# 3. Deploy by linking to an explicit lowercase project name (avoids automatic name inference)
cd /Users/mac/ws/claude/CTI
vercel link --project cti-sentinel --yes
vercel deploy

Takeaway

#

The local directory name and the deployed project name are independent — use that to get around the validation rule without ever renaming the directory itself, via vercel link --project <lowercase-name>.