vitest-dev/vitest · error · TypeError

vitest.mergeReports() expects all paths in

Error message

vitest.mergeReports() expects all paths in "${blobsDirectory}" to be files generated by the blob reporter, but "${filename}" is not a file

What it means

`vitest.mergeReports()` reads every entry in the blobs directory and expects each to be a regular file produced by the blob reporter. If an entry is a subdirectory or other non-file (so `stats.isFile()` is false), the merge aborts with a `TypeError` naming the offending entry.

Solutions

Inspect the blobs directory and remove any subdirectories.
Use a dedicated directory that only ever receives blob output.
Clean the directory (`rm -rf blobs/*`) before each merge-reports run.

Example fix

# before
vitest --merge-reports=.   # repo root contains node_modules/, .git/

# after
vitest --merge-reports=./blobs   # dedicated dir, files only

Defensive patterns

Strategy: try-catch

Validate before calling

import { readdir, stat } from 'node:fs/promises'
import { resolve } from 'node:path'

async function assertBlobsDirHasOnlyFiles(dir: string) {
  for (const name of await readdir(dir)) {
    const s = await stat(resolve(dir, name))
    if (!s.isFile()) {
      throw new Error(`'${name}' in blobs dir is not a file; remove it before merging.`)
    }
  }
}

Try / catch

try {
  await vitest.mergeReports(version, blobsDir, projects)
} catch (e) {
  if (e instanceof TypeError && e.message.includes('is not a file')) {
    // clean subdirectories from the blobs dir, then retry once
    await cleanNonFiles(blobsDir)
    return vitest.mergeReports(version, blobsDir, projects)
  }
  throw e
}

Prevention

Dedicate a directory to blob output only — never reuse a build/output dir.
Clean the blobs directory before each generate/merge cycle.

When it happens

Trigger: Calling `--merge-reports <dir>` (or `vitest.mergeReports()`) where `readdir(dir)` yields a subdirectory, e.g. a leftover `.git`, `node_modules`, or nested output folder.

Common situations: Pointing `--merge-reports` at the repo root or a directory shared with other build artifacts; a previous run left a subdirectory in the blobs folder.

Related errors

AI-assisted analysis of vitest-dev/vitest@1fa9837ec2 (2026-08-11). Data as JSON: /api/errors/ab015487f91a9b7d. Report an issue: GitHub.

Appendix: source

Thrown at packages/vitest/src/node/reporters/blob.ts:125

    }

    this.ctx.logger.log('blob report written to', outputFile)
  }
}

export async function readBlobs(
  currentVersion: string,
  blobsDirectory: string,
  projectsArray: TestProject[],
): Promise<MergedBlobs> {
  // using process.cwd() because --merge-reports can only be used in CLI
  const resolvedDir = resolve(process.cwd(), blobsDirectory)
  const blobsFiles = await readdir(resolvedDir)
  const promises = blobsFiles.map(async (filename) => {
    const fullPath = resolve(resolvedDir, filename)
    const stats = await stat(fullPath)
    if (!stats.isFile()) {
      throw new TypeError(
        `vitest.mergeReports() expects all paths in "${blobsDirectory}" to be files generated by the blob reporter, but "${filename}" is not a file`,
      )
    }
    const content = await readFile(fullPath, 'utf-8')
    const [version, files, errors, coverage, executionTime, environmentModules] = parse(
      content,
    ) as MergeReport
    if (!version) {
      throw new TypeError(
        `vitest.mergeReports() expects all paths in "${blobsDirectory}" to be files generated by the blob reporter, but "${filename}" is not a valid blob file`,
      )
    }
    return { version, files, errors, coverage, file: filename, executionTime, environmentModules }
  })
  const blobs = await Promise.all(promises)

  if (!blobs.length) {
    throw new Error(

View on GitHub (pinned to 1fa9837ec2)