dotenv Not Loading? Step-by-Step Debugging Guide
Fix environment variables not loading from .env files. Covers Node.js, Python, Docker, file path issues, syntax errors, load order, and production gotchas.
Last updated:
Frequently Asked Questions
Why is my .env file not being loaded?
The most common causes are: the dotenv package is not installed or not imported early enough, the .env file is not in the working directory, there are syntax errors in the file, or you are in production where .env files are not used.
Does dotenv work in production?
Most dotenv libraries load .env files but do not override existing environment variables. In production, set real environment variables through your hosting platform, CI/CD pipeline, or container orchestration. The .env file is for local development only.
Why are my environment variables undefined after dotenv.config()?
Check that dotenv.config() is called before any module that reads process.env. In Node.js, imports are hoisted, so use require("dotenv").config() at the very top of your entry file, or use node --env-file=.env (Node 20.6+).
Stay up to date
Get notified about new guides, tools, and cheatsheets.
Related Cheatsheets
Cheatsheet
Docker Cheat Sheet
Quick reference for Docker CLI: containers, images, volumes, networking, and Docker Compose.
Cheatsheet
Python Cheat Sheet — Quick Reference
Python quick reference: data types, string methods, list/dict comprehensions, f-strings, file I/O, and common standard library modules.
Related Guides
Node.js Environment Variables: process.env, dotenv & --env-file
How to use environment variables in Node.js. Covers process.env, dotenv, Node 20.6+ --env-file flag, NODE_ENV, type-safe validation with zod, and cross-platform support.
Python Environment Variables: os.environ, dotenv, and Pydantic
How to read, set, and manage environment variables in Python. Covers os.environ, python-dotenv, Pydantic Settings, Django, and Flask patterns.
Docker Environment Variables: Dockerfile ENV, ARG & Runtime
How to use environment variables in Docker: ENV vs ARG in Dockerfile, docker run -e, --env-file, multi-stage builds, BuildKit secrets, and best practices.