Vercel ENV Variable Missing Beginner Guide: quick fix, steps, and deep guide

Q: Vercel ENV Variable Missing Beginner Guide

Treat this as a Vercel troubleshooting issue. Confirm the environment, inputs, permissions, logs, and delivery boundary, then use the linked deep guide for the full checklist.

What is the problem?

Vercel 部署 Next.js 项目时经常因为环境变量缺失失败。本文解释什么是环境变量、如何看日志、如何使用 .env.example、什么时候不能让客户直接发真实密钥。

Quick solution

Treat this as a Vercel troubleshooting issue. First confirm the environment, inputs, permissions, logs, and delivery boundary. Then use the linked deep guide for the full checklist before changing production code or promising a result.

Read the deep guide

Detailed steps

打开 Vercel 部署日志，搜索 `env`、`process.env`、`missing`、`required`、`undefined`。
记录缺少的变量名，不要只记错误截图。
在项目里搜索变量：
查看是否有 `.env.example`。如果没有，可以自己整理一份，但不要写真实密钥。
判断变量类型。以 `NEXT_PUBLIC_` 开头的变量会暴露给浏览器，不能放秘密值。
在 Vercel 项目里进入 Environment Variables，选择 Production 和 Preview，添加变量名和值。

Commands or code

rg "process.env|NEXT_PUBLIC|DATABASE_URL|API_KEY"

Risk notes

Confirm the real project environment, account permissions, platform rules, and output quality before delivery. Do not ship AI-generated changes without human review, and do not claim indexing, income, deployment success, or ranking improvements without measured evidence.