vitest-dev/vitest · error · Error

The " " is not defined in the configuration. Available tags…

Error message

The ${prefix} "${tag}" is not defined in the configuration. Available tags are:
${availableTags.map(t => `- ${t.name}${t.description ? `: ${t.description}` : ''}`).join('\n')}

What it means

Thrown by createNoTagsError when the config DOES define tags but the specific tag referenced by a test, suite, or CLI filter is not among them. Unlike error 340, this path lists the available tag names (with descriptions) to guide correction. It is reached from validateTags, suite.ts:322 (tag application), and resolveTagPattern (wildcard/non-wildcard filter resolution).

Solutions

1. Read the 'Available tags are:' list in the error and use one of those exact names.
2. Add the missing tag to config.tags, e.g. append `{ name: 'e2e' }`.
3. Fix the typo / casing in the test's `tags` option to match a declared tag.
4. Set `strictTags: false` if loose tagging is acceptable for the project.
5. For wildcard filters, ensure the pattern matches at least one declared tag name.

Example fix

// before — config declares 'integration' but test says 'integ'
test('db', { tags: ['integ'] }, () => {})

// after
test('db', { tags: ['integration'] }, () => {})

import type { TestTagDefinition } from 'vitest'
const declared = new Set((config.tags ?? []).map((t: TestTagDefinition) => t.name))
function assertKnownTag(tag: string) {
  if (!declared.has(tag)) {
    throw new Error(`Tag '${tag}' is not declared. Known: ${[...declared].join(', ')}`)
  }
}

function isKnownTag(declared: ReadonlySet<string>, tag: string): boolean {
  return declared.has(tag)
}

When it happens

Trigger: config.tags is non-empty (e.g. [{name:'smoke'},{name:'integration'}]) but a test uses a tag not in that list, e.g. `{ tags: ['e2e'] }`. Also triggered by `--tag e2e` on the CLI, or a wildcard pattern like `--tag 'e2e-*'` that matches no declared tag.

Common situations: Typos in tag names (case or spelling); renaming a tag in config but not in tests; a tag added to a shared test file by one team that another team's config doesn't declare; wildcard patterns that don't match any declared tag.

Related errors

• Each tag defined in "test.tags" must have a "name"…
• Tag name " " is already defined in "test.tags". Tag names…
• Tag name " " is invalid. Tag names cannot contain spaces.
• Tag name " " is invalid. Tag names cannot be a logical…
• Tag name " " is invalid. Tag names cannot contain "!", "*"…

AI-assisted analysis of vitest-dev/vitest@1fa9837ec2 (2026-08-11). Data as JSON: /api/errors/77816376d9815727. Report an issue: GitHub.

Appendix: source

Thrown at packages/vitest/src/runtime/runner/utils/tags.ts:41

export function validateTags(config: SerializedConfig, tags: string[]): void {
  if (!config.strictTags) {
    return
  }

  const availableTags = new Set(config.tags.map(tag => tag.name))
  for (const tag of tags) {
    if (!availableTags.has(tag)) {
      throw createNoTagsError(config.tags, tag)
    }
  }
}

export function createNoTagsError(availableTags: TestTagDefinition[], tag: string, prefix = 'tag'): never {
  if (!availableTags.length) {
    throw new Error(`The Vitest config does't define any "tags", cannot apply "${tag}" ${prefix} for this test. See: https://vitest.dev/guide/test-tags`)
  }
  throw new Error(`The ${prefix} "${tag}" is not defined in the configuration. Available tags are:\n${availableTags
    .map(t => `- ${t.name}${t.description ? `: ${t.description}` : ''}`)
    .join('\n')}`)
}

export function createTagsFilter(tagsExpr: string[], availableTags: TestTagDefinition[]): (testTags: string[]) => boolean {
  const matchers = tagsExpr.map(expr => parseTagsExpression(expr, availableTags))
  return (testTags: string[]) => {
    return matchers.every(matcher => matcher(testTags))
  }
}

type TagMatcher = (tags: string[]) => boolean

function parseTagsExpression(expr: string, availableTags: TestTagDefinition[]): TagMatcher {
  const tokens = tokenize(expr)
  const stream = new TokenStream(tokens, expr)
  const ast = parseOrExpression(stream, availableTags)
  if (stream.peek().type !== 'EOF') {

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