vitest-dev/vitest · error · Error

the blobs in "${blobsDirectory}" were generated by a differe

Error message

the blobs in "${blobsDirectory}" were generated by a different version of Vitest. Expected v${currentVersion}, but received v${blobs[0].version}

What it means

Thrown by `readBlobs` (blob.ts:157) when all blob files share one version but that version differs from `currentVersion` (the version of the Vitest process performing the merge). Because the merge step must deserialize and rehydrate blob structures into the current process, the formats must match exactly; a mismatch is rejected even though the blobs are internally consistent.

Source

Thrown at packages/vitest/src/node/reporters/blob.ts:157

    return { version, files, errors, coverage, file: filename, executionTime, environmentModules, transformTime }
  })
  const blobs = await Promise.all(promises)

  if (!blobs.length) {
    throw new Error(
      `vitest.mergeReports() requires at least one blob file in "${blobsDirectory}" directory, but none were found`,
    )
  }

  const versions = new Set(blobs.map(blob => blob.version))
  if (versions.size > 1) {
    throw new Error(
      `vitest.mergeReports() requires all blob files to be generated by the same Vitest version, received\n\n${blobs.map(b => `- "${b.file}" uses v${b.version}`).join('\n')}`,
    )
  }

  if (!versions.has(currentVersion)) {
    throw new Error(
      `the blobs in "${blobsDirectory}" were generated by a different version of Vitest. Expected v${currentVersion}, but received v${blobs[0].version}`,
    )
  }

  // Restore module graph
  const projects = Object.fromEntries(
    projectsArray.map(p => [p.name, p]),
  )

  blobs.forEach((blob) => {
    Object.entries(blob.environmentModules).forEach(([projectName, modulesByProject]) => {
      const project = projects[projectName]
      if (!project) {
        return
      }

      modulesByProject.external.forEach(([id, externalized]) => {
        project._resolver.externalizeCache.set(id, externalized)

View on GitHub (pinned to d568f8ce37)

Solutions

Run the merge step with the exact same Vitest version that wrote the blob files.
Upgrade (or downgrade) the Vitest used to write the blobs to match the merging process, then regenerate.
Install Vitest locally in the project so both CI and local use the same binary (`npx vitest --merge-reports`).

Example fix

# before: versions differ
vitest --reporter=blob        # v3.0.0 in CI
vitest --merge-reports dir    # v3.1.0 locally
# after: match versions
npx vitest@3.0.0 --merge-reports dir

Defensive patterns

Strategy: validation

Validate before calling

import { readdirSync, readFileSync } from 'node:fs'
import { resolve } from 'node:path'
import { parse } from 'flatted'
import { version } from 'vitest/package.json'
const blobVersion = (parse(readFileSync(resolve(blobsDirectory, readdirSync(blobsDirectory)[0]), 'utf-8')) as any[])[0]
if (blobVersion !== version) throw new Error(`Merge Vitest v${version} != blob v${blobVersion}`)

Prevention

Use the same locally-installed Vitest (`npx vitest`) for both writing and merging blobs.
Pin the Vitest version in CI and locally.
After upgrades, regenerate all blobs before merging.

When it happens

Trigger: Generating blobs with Vitest 3.0.0 and running `vitest --merge-reports` with Vitest 3.1.0; a local merge run using a globally installed `vitest` whose version differs from the one used in CI to write the blobs.

Common situations: Local/global Vitest version drift; CI wrote blobs with one version and the merge step uses another; upgrading Vitest between the blob run and the merge run.

Related errors

AI-assisted analysis of vitest-dev/vitest@d568f8ce37 (2026-08-03). Data as JSON: /data/errors/78ed63671e8c5c01.json. Report an issue: GitHub.