fix(nextjs): handle missing varlock binary on serverless platforms#651
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theoephraim merged 1 commit intomainfrom Apr 23, 2026
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fix(nextjs): handle missing varlock binary on serverless platforms#651theoephraim merged 1 commit intomainfrom
theoephraim merged 1 commit intomainfrom
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Two issues caused "Cannot find module 'varlock'" and "Unable to find
varlock executable" errors on Vercel with recent Next.js versions:
1. Vercel's builder now always uses the bundled server path, which
inlines @next/env so @vercel/nft no longer traces its dependencies.
Fix: split tsup config so next-env-compat bundles varlock modules
directly (noExternal), eliminating external require('varlock') calls.
2. The varlock CLI binary is not available at runtime on serverless
platforms. Fix: call execSyncVarlock with exitOnError:false and
handle errors in loadEnvConfig's catch block — when the binary is
not found in production, defer to the init bundle injected into the
webpack/turbopack runtime.
Also removes stale exports (varlock-env-inline, edge-env).
Fixes #584
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The changes in this PR will be included in the next version bump.
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Summary
On serverless platforms (Vercel, AWS Lambda), the varlock CLI binary is not available at runtime. When
___next_launcher.cjsloads@next/env(ournext-env-compat.js) and callsloadEnvConfig(),execSyncVarlockwould crash with "Unable to find varlock executable".Two issues prevented the catch block from handling this gracefully:
exitOnError: true—execSyncVarlockcalledprocess.exit(1)internally before the error could reach our catch blockshowLogsOnError: true— the error was printed to stderr even when it should be silently deferredChanges
showLogsOnError: falseandexitOnError: falseso all error handling is inloadEnvConfig's catch blockprocess.env)process.exitin prodFixes #584
Test plan
loadEnvConfigreturns cleanly with no stderrnext buildon example app — works normallynext devwithout varlock installed — confirm clear error message