TypeScript 7 migration: tsconfig errors and how to fix

TypeScript 7.0 is a native port of the TypeScript compiler, written in Go, and it reached general availability in July 2026. It is far faster, but npm install -D typescript now installs it, and it turns many old tsconfig.json options into hard errors. If your build broke after an upgrade, the cause is almost always a removed flag, a new default, or a tool that needs the old compiler API. This guide lists each change, the fix, and the tools that must wait for TypeScript 7.1.

What changed in TypeScript 7

According to a TypeScript 7.0 migration playbook, the release candidate shipped June 18, 2026 and the stable build followed on July 8. InfoWorld's report puts the speedup at 8x to 12x on full builds.

The playbook lists Microsoft's published benchmarks:

Codebase	TypeScript 6	TypeScript 7	Speedup
VS Code (default settings)	125.7 s	10.6 s	11.9x
Sentry	139.8 s	15.7 s	8.9x
Bluesky	24.3 s	2.8 s	8.7x
Playwright	12.8 s	1.47 s	8.7x
tldraw	11.2 s	1.46 s	7.7x

Treat these as vendor-published measurements. Your own project will land somewhere in that range, depending on codebase size and processor count.

Why your build broke: the new defaults

TypeScript 7 defaults are stricter than TypeScript 6, and several now apply without any setting in your config. The playbook's defaults section names these:

• strict is on by default.
• module defaults to esnext.
• types defaults to an empty array, so no @types package loads unless you list it.
• rootDir defaults to ./.
• noUncheckedSideEffectImports is on.
• Type ordering is stable and not configurable.

The empty types default creates the most confusion. For example, a project that relied on @types/node loading automatically will suddenly report that process or Buffer is missing. Add the packages back explicitly:

{
  "compilerOptions": {
    "types": ["node"]
  }
}

Options that now fail with hard errors

TypeScript 7 stops accepting a list of legacy options. According to the removed-options list, these now produce errors instead of warnings:

Removed or rejected	What to do instead
target: es5, downlevelIteration	Use es2015 or newer
module: amd, umd, systemjs, none	Use esnext, nodenext or commonjs
moduleResolution: node, node10, classic	Use bundler or nodenext
baseUrl	Use paths with relative targets, or package imports
esModuleInterop: false, allowSyntheticDefaultImports: false	Remove them and accept the default
alwaysStrict: false	Remove it
Import assert syntax	Use with
module keyword in namespace declarations	Use namespace

Two other changes are easy to miss. Passing a bare file path to tsc while a tsconfig.json exists is now an error, and you need --ignoreConfig to bypass it. Template literal types also treat Unicode code points, such as emoji, as single units instead of surrogate pairs.

Fix these on TypeScript 6 first. The cleanest path is removing the legacy options while you are still on 6.x, then upgrading. That way each compiler error has exactly one explanation.

How to migrate step by step

The playbook gives a seven-step migration order. Here is the same plan in plain terms:

1. Remove baseUrl, target: es5 and old moduleResolution values while on 6.x.
2. Run npm install -D typescript. This installs 7.0 under the latest tag.
3. Run tsc --noEmit. Sort the errors into config problems and real strict-mode errors.
4. Add back only the @types packages you actually use.
5. Install the compatibility package if a tool needs the old API. More on that below.
6. Switch your editor to the native language server.
7. Tune CI with the new parallel flags.

Run step 3 before modifying any application code. A configuration error usually needs a one-line correction. A strict-mode error requires a genuine source change, and combining the two investigations wastes considerable time.

Which tools break, and the shim that helps

The @typescript/typescript6 package is a compatibility shim. It provides a tsc6 binary and re-exports the TypeScript 6.0 programmatic API, so tsc 7.0 and older tools can coexist, as the compatibility notes and InfoWorld's coverage describe.

The ecosystem breakdown splits tools into what works now and what must wait for TypeScript 7.1, which is due to ship a new programmatic API with no date announced:

Tool or stack	Status today
Next.js and React app code	Safe to upgrade
Plain Node services	Safe to upgrade
VS Code and Visual Studio	Native preview extension becomes default
typescript-eslint	Works through the @typescript/typescript6 shim
Vue (Volar templates)	Blocked until 7.1
Angular template checking	Blocked; split setup possible (TS 7 tsc, TS 6 editor)
Svelte, Astro, MDX	Embedded-language tooling blocked until 7.1

typescript-eslint is a linting toolchain that reads type information through the compiler API. That is why it needs the shim. If you also upgraded Next.js this year, you may have seen the tooling change covered in Next.js 16 Deleted next lint. Here's the Fix.

Consider a monorepo with a React app and a Vue admin panel. Upgrade the React packages to 7.0 now. Keep the Vue package on 6.x with the shim until 7.1 arrives.

Tuning CI for the new compiler

TypeScript 7 runs checks in parallel, and the CI tuning section lists three flags:

• --checkers 8 raises the number of parallel type checkers. The playbook reports VS Code dropping from 10.6 s to 7.51 s with it.
• --builders parallelizes project references.
• --singleThreaded helps on constrained runners.

Vendor-reported results show the payoff. The playbook says Slack cut type-check time from 7.5 minutes to 1.25 minutes and reduced its merge queue by 40 percent. Canva reported editor first-error latency falling from 58 s to 4.8 s. These come from the companies themselves, so test your own repository before you promise a number to your team.

Should you upgrade now or wait?

Upgrade now if your project is application code without custom compiler plugins. The performance improvement is substantial, and the configuration corrections are mechanical.

Wait, or use the split setup, if you depend on Vue, Angular, Svelte or Astro template checking. Those paths need TypeScript 7.1.

Pin the version while you evaluate the decision. Set an exact version in package.json so a fresh install does not move you to 7.0 by accident. Other major upgrades this quarter bring their own checklists, such as PostgreSQL 19 breaking changes to check before upgrading and Java 27 is not LTS: should you leave Java 25?