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Next.Js 16.3 TypeScript Version Check Breaks Monorepo Aliases

Next.js 16.3 introduced a minimum TypeScript version requirement of >=7.0.0, but its dependency verification uses the `typescript` package name and treats aliased packages (e.g., pnpm alias `typescript` to v6 and `@typescript/native` to v7) as missing or incompatible, causing builds to fail and auto-install attempts to fail.

highConfidence 85%Next.js Affected V16.3.0

Origin Analysis

Next.js 16.3 added a dependency validation step that checks the installed `typescript` package version against a minimum required version (>=7.0.0). In monorepos using pnpm aliases, the `typescript` package resolves to v6 while v7 is installed under `@typescript/native`. The validation fails because the resolved `typescript` version is below the minimum, triggering an automatic install of `typescript@latest` that conflicts with the alias and fails, causing the build to abort.

1. Clone the repo https://github.com/lourd/next-16.3-monorepo-bug 2. Run `pnpm install` 3. Run `pnpm nx build my-app` or cd into `apps/my-app` and run `pnpm next build` or `pnpm next dev` 4. Observe the error: `It looks like you're trying to use TypeScript but do not have the required package(s) installed.` and failed auto-install.

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

The patch adds a new config option but does not change default behavior. No breaking changes for existing users. To roll back, revert the patch or set `skipTypeScriptCheck: false`. Potential risk: if users enable this option and later have no valid TypeScript installation, Next.js will fail later during `tsc` invocation with a less clear error; ensure documentation clearly states that the option is for advanced setups. Additionally, future Next.js versions may change internal function signatures, so this patch may need to be updated when upgrading.