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Turbopack External Module Hash Mismatch With Pnpm In Cross-Environment Deployment

Next.js 16 with Turbopack generates external module references with content-based hashes that depend on the node_modules directory structure at build time. When deploying to a different environment and reinstalling dependencies (especially with pnpm symlinks), the hashes no longer match the installed packages, causing the production server to fail to start with 'Cannot find module' errors.

criticalConfidence 85%Next.js Affected V16.0.0 Affected V16.1.1

Origin Analysis

Turbopack computes a hash for external modules based on the node_modules layout (including pnpm's symlink paths) during the build and embeds this hash in the runtime require statements. After reinstallation in a different environment, the node_modules structure changes, making the embedded hash point to a non-existent module name.

1. Create a Next.js 16.1.1+ project with OpenTelemetry instrumentation. 2. Add instrumentation.ts that imports @opentelemetry/auto-instrumentations-node. 3. Build the project in CI/CD using pnpm install --frozen-lockfile followed by next build. 4. Archive the build output excluding node_modules. 5. Extract the archive in a different environment. 6. Run pnpm install to reinstall dependencies. 7. Run next start and observe the 'Cannot find module require-in-the-middle-a99415fa67232f7f' error.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

Switching to Webpack may significantly increase build time and could introduce Webpack-specific behavior differences. Rollback: change the build script back to 'next build' once the official fix is available. For teams that require minimal build time, monitor CI performance and consider using output: 'standalone' as an alternative mitigation, though it may have its own deployment implications.