payloadcms/payload · error · APIError

Attachment is missing filename

Error message

Attachment is missing filename

What it means

Thrown by mapAttachments in the Resend adapter when an attachment object is missing the required `filename` field. Resend's API requires a filename for every attachment, so the adapter validates this before building the request rather than letting Resend reject the whole send.

Source

Thrown at packages/email-resend/src/index.ts:152

  }

  if (Array.isArray(addresses)) {
    return addresses.map((address) => (typeof address === 'string' ? address : address.address))
  }

  return [addresses.address]
}

function mapAttachments(
  attachments: SendEmailOptions['attachments'],
): ResendSendEmailOptions['attachments'] {
  if (!attachments) {
    return []
  }

  return attachments.map((attachment): Attachment => {
    if (!attachment.filename) {
      throw new APIError('Attachment is missing filename', 400)
    }

    if (!attachment.content && !attachment.path) {
      throw new APIError('Attachment is missing both content and path', 400)
    }

    // When both content and path are provided, content takes priority; path is ignored.
    if (attachment.path && !attachment.content) {
      const path = typeof attachment.path === 'string' ? attachment.path : attachment.path.href
      return {
        filename: attachment.filename,
        path,
      }
    }

    if (typeof attachment.content === 'string') {
      return {
        content: attachment.content,

View on GitHub (pinned to 00c58b35c0)

Solutions

1. Ensure every attachment object includes a `filename` string (including extension).
2. Default filename to a sensible value (e.g. originalname or 'attachment.bin') when the source object omits it.
3. Validate the attachments array shape before calling payload.sendEmail.

Example fix

// before
attachments: [{ content: buf }]
// after
attachments: [{ filename: 'report.pdf', content: buf }]

function normalizeAttachments(attachments) {
  return (attachments || []).map(a => {
    if (!a.filename) throw new Error('Attachment is missing filename')
    return a
  })
}

const attachmentHasFilename = (a) => Boolean(a && a.filename)

When it happens

Trigger: Calling payload.sendEmail with `attachments: [{ content: buffer }]` (no filename), or constructing attachments dynamically where the filename key is omitted/undefined.

Common situations: Building attachments from uploaded files and forgetting to map the original name to filename; renaming fields and missing one code path; attachments coming from a third-party payload that omits filename.

Related errors

• Attachment is missing both content and path
• Attachment content must be a string or a buffer
• Error sending email: ${statusCode}
• Username or email is required
• Email is required.

AI-assisted analysis of payloadcms/payload@00c58b35c0 (2026-08-12). Data as JSON: /api/errors/72c65d2f9bc71758. Report an issue: GitHub.