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Fix Environment Variables That Work Locally but Are Undefined in Production

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Self-Hosting & Infra beginner 6 min read $0.01 Updated 2026-10-19

Why environment variables go missing in production: dotenv not loaded, build-time vs runtime variables, NEXT_PUBLIC and VITE prefixes, containers and systemd not inheriting a shell, quoting and whitespace, serverless config and redeploy requirements.

The app reads undefined or an empty value after deploy. Check where the variable is set, when it is read (build vs runtime), prefixes for client bundles, quoting, and which process actually sees it.

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#environment-variables#deployment#dotenv#configuration#troubleshooting

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