Blob troubleshooting

Diagnose disabled runtime config, missing Cloudflare R2 bindings, missing Vercel tokens, failed lookups, and upload validation errors.

Use this page by symptom. Each section gives the likely cause, the fix, and a quick verification step.

`Blob runtime is disabled.`

Cause: Blob runtime config resolved to false, or the integration was not registered.

Fix: Register the Vite plugin or Nitro module and avoid setting blob: false unless you intentionally want to disable Blob.

vite.config.ts

export default defineConfig({
  plugins: [hubBlob()],
  blob: {
    driver: 'fs',
  },
})

Verify: Call a route that returns await blob.list().

Cause: Blob is using the Cloudflare R2 driver, but the runtime request environment does not include the configured binding.

Fix: Add an R2 binding named BLOB, or set blob.binding to the binding name you already use.

blob: {
  driver: 'cloudflare-r2',
  binding: 'FILES',
  bucketName: 'assets',
}

Verify: Call the route inside the Cloudflare runtime where the binding exists.

Cause: Blob resolved Cloudflare R2, but no bucketName was available during config resolution.

Fix: Set bucketName in config, or set BLOB_BUCKET_NAME or CLOUDFLARE_R2_BUCKET_NAME before building.

BLOB_BUCKET_NAME=assets pnpm build

Verify: Inspect the generated Cloudflare output for an R2 bucket binding.

Cause: Blob resolved vercel-blob, but the runtime did not provide BLOB_READ_WRITE_TOKEN.

Fix: Set the token in the environment where the app runs.

BLOB_READ_WRITE_TOKEN=<blob-read-write-token>

Verify: Restart the app or redeploy, then call a route that writes with blob.put().

Cause: blob.head() did not find the pathname. Unlike blob.get(), head() throws a 404 for missing objects.

Fix: Use blob.get() when missing objects are part of normal control flow.

const file = await blob.get(pathname)

if (!file) {
  throw createError({ statusCode: 404, statusMessage: 'File not found' })
}

Verify: List the prefix that should contain the object and compare the returned pathname values.

Cause: blob.serve() could not load the requested object body.

Fix: Validate the pathname passed to serve() and confirm the object exists with blob.list() or blob.get().

Verify: Call blob.get(pathname) from the same route or runtime.

Cause: ensureBlob() was called without validation rules.

Fix: Pass maxSize, types, or both.

ensureBlob(file, {
  maxSize: '1MB',
  types: ['image'],
})

Verify: Upload a valid file and confirm the route reaches blob.put().

Cause: Vercel hosting requires Vercel Blob-backed storage, but Blob resolved the fs driver.

Fix: Set BLOB_READ_WRITE_TOKEN or configure blob.driver as vercel-blob.

blob: {
  driver: 'vercel-blob',
}

Verify: Restart or rebuild. The warning should disappear.