---
title: Fix Vitest 5 test.sequential Removed Error
description: Fix Vitest 5 removing test.sequential, describe.sequential, and the sequential option. Replace them with concurrent: false.
date: 2026-08-13T00:00:00.000Z
category: guides-fixes
tags: vitest, testing, javascript
---

## Quick Answer

Vitest 5 removes `test.sequential`, `describe.sequential`, and the `sequential` boolean option outright, not deprecated-with-warning. Vitest's migration guide doesn't document a specific runtime error for calling them; expect a type error or a plain "is not a function" failure, since it's no longer a recognized API surface. Replace `test.sequential('name', fn)` with `test('name', { concurrent: false }, fn)`.

## Why this got removed instead of deprecated

`concurrent` and `sequential` described the same thing from two directions. A test was either allowed to run concurrently with its siblings or it wasn't, and `sequential` only ever meant "not concurrent." [Vitest's own migration guide](https://main.vitest.dev/guide/migration) states the removal directly, in the section covering these removed options:

> Vitest 5.0 removes the deprecated `test.sequential`, `describe.sequential`, and `sequential` test options. Use `concurrent: false` when you need a test or suite to opt out of inherited or globally configured concurrency.

The redundancy is what made this a removal candidate rather than a permanent pair of options. [The GitHub issue that proposed this change](https://github.com/vitest-dev/vitest/issues/10180) lists out the full set of ways Vitest let you express test concurrency, including combinations like `{ sequential: false }`, and points out that having two independent flags that can contradict each other (is `{ concurrent: false, sequential: false }` concurrent or not?) creates internal churn and reader confusion for no real benefit. Collapsing to one flag, `concurrent`, removes the ambiguity entirely.

<Callout type="warning" title="Not a warning, an outright removal">
  This isn't the usual deprecate-then-remove cycle where a warning gives you a
  release or two of runway. `test.sequential`, `describe.sequential`, and the
  `sequential` option object key are gone in Vitest 5.0. If your suite still
  calls any of them, the upgrade breaks that suite immediately, not on some
  future major version.
</Callout>

## Fix it: switch to concurrent: false

Vitest's migration guide documents the exact replacement pattern for all three removed forms. Each is a mechanical rename, not a behavior change.

```ts title="calculator.test.ts - test.sequential (removed)"
test.sequential("example", async () => {
  /* ... */
}); // BROKEN: test.sequential no longer exists in Vitest 5
```

```ts title="calculator.test.ts - concurrent: false (fixed)"
test("example", { concurrent: false }, async () => {
  /* ... */
}); // FIXED: same effect, using the surviving option
```

`describe.sequential` follows the identical pattern:

```ts title="calculator.test.ts - describe.sequential (removed)"
describe.sequential("suite", () => {
  /* ... */
}); // BROKEN: describe.sequential no longer exists in Vitest 5
```

```ts title="calculator.test.ts - concurrent: false (fixed)"
describe("suite", { concurrent: false }, () => {
  /* ... */
}); // FIXED: same effect, using the surviving option
```

If your code used the `sequential` option-object key instead of the chained method, the same replacement applies directly to that key:

```ts title="calculator.test.ts - sequential: true option key (removed)"
test("example", { sequential: true }, async () => {
  /* ... */
}); // BROKEN: sequential key no longer recognized
```

```ts title="calculator.test.ts - concurrent: false (fixed)"
test("example", { concurrent: false }, async () => {
  /* ... */
}); // FIXED: negate the surviving flag instead
```

Search your suite for `.sequential(` and `sequential:` before you upgrade, not after. Every match needs this exact rename, and there's no runtime compatibility shim carrying the old name forward.

## Confirmed version range

Documented in [Vitest's own current migration guide](https://main.vitest.dev/guide/migration) as an intentional Vitest 5.0 removal, in the section covering the removed `sequential` options. Corroborated by [vitest-dev/vitest#10180](https://github.com/vitest-dev/vitest/issues/10180), the issue that proposed consolidating concurrency into the single `concurrent` flag. This repository's own `vitest.config.ts` is pinned to `vitest@^3.0.0`, so this removal wasn't independently reproduced against this project's build; every claim above traces back to Vitest's migration guide and the linked issue, not a local repro.

More fixes like this one are in the [Guides & Fixes](/guides-fixes) archive, and every Vitest post is tagged under [vitest](/tag/vitest). If your suite is also hitting the hoisted-mocking change in the same upgrade, see [Fix Vitest 5 vi.mock Top-Level Scope Error](/guides-fixes/fix-vitest-5-vi-mock-top-level-scope-error/). Running `vitest` from a subdirectory in the same upgrade? See [Fix Vitest 5 Config Not Found in Parent Directory](/guides-fixes/fix-vitest-5-config-not-found-parent-directory/).