vitest-dev/vitest · error · Error

Unexpected numerical input for "memoryLimit"

Error message

Unexpected numerical input for "memoryLimit"

What it means

stringToBytes (memory-limit.ts:99-101) throws when the numeric input is not a positive value: a number <= 0, NaN, or otherwise invalid. The branch handles the leftover case after the fraction (0,1] and the absolute (>1) cases are excluded.

Source

Thrown at packages/vitest/src/utils/memory-limit.ts:100

    }
  }

  if (typeof input === 'number') {
    if (input <= 1 && input > 0) {
      if (percentageReference) {
        return Math.floor(input * percentageReference)
      }
      else {
        throw new Error(
          'For a percentage based memory limit a percentageReference must be supplied',
        )
      }
    }
    else if (input > 1) {
      return Math.floor(input)
    }
    else {
      throw new Error('Unexpected numerical input for "memoryLimit"')
    }
  }

  return null
}

View on GitHub (pinned to d568f8ce37)

Solutions

1. Use a positive absolute value or a valid percentage string for vmMemoryLimit.
2. Omit vmMemoryLimit entirely (or set to undefined) to let Vitest compute a sensible default.
3. Sanitize external/env inputs before assigning them to vmMemoryLimit.

Example fix

// before: invalid value
export default defineConfig({ test: { vmMemoryLimit: 0 } })
// or env-derived
const limit = Number(process.env.LIMIT) // NaN

// after: valid or omitted
export default defineConfig({ test: { vmMemoryLimit: '1GB' } })
// or sanitize
const limit = Number(process.env.LIMIT)
export default defineConfig({ test: Number.isFinite(limit) && limit > 1 ? { vmMemoryLimit: limit } : {} })

function validateMemoryLimitNumber(input: unknown) {
  if (typeof input !== 'string' && typeof input !== 'number') return
  const numeric = typeof input === 'string' ? Number.parseFloat(input) : input
  if (!Number.isFinite(numeric) || numeric <= 0) {
    throw new Error(`memoryLimit must be a positive number or a valid memory string; received '${String(input)}'`)
  }
}

When it happens

Trigger: Providing a vmMemoryLimit (or calling stringToBytes) with 0, a negative number, or a string that parses to NaN/0 — e.g. '0', '-512', 'abc', or an empty numeric portion.

Common situations: Typing vmMemoryLimit: 0 thinking it disables the limit; a negative value from an env-var parse; a malformed string like '--gb' whose numeric portion is empty and resolves to 0.

Related errors

• For a percentage based memory limit a percentageReference mu
• Environment "${name}" is not a valid environment. Path "${pa
• Tag "${tag.name}": priority must be a non-negative number.
• Unknown value for "test.listTags": ${listTags}
• Expected config.test.coverage.thresholds to be an object

AI-assisted analysis of vitest-dev/vitest@d568f8ce37 (2026-08-03). Data as JSON: /data/errors/d290d84258712e12.json. Report an issue: GitHub.