Web Messaging Guest API: File upload 413 on 4.8MB PNG despite 10MB config

NICE CXone API & Integrations
1

Stuck on the file upload flow for the Web Messaging Guest API. The org settings show a 10MB limit for file attachments, but the SDK client throws a 413 Payload Too Large when sending a 4.8MB PNG. Smaller files (under 2MB) work fine.

Here’s the upload sequence:

  1. Get the upload URL via POST /api/v2/guests/fileuploads with the file metadata.
  2. Receive the uploadUrl and uploadToken.
  3. Perform PUT to the uploadUrl with the file body.

The PUT request fails with 413. Checked the headers; Content-Length matches the file size. No custom middleware blocking it.

  • Genesys Cloud Web Messaging SDK v1.12.0
  • Node.js 18 runtime for the backend proxy
  • File: 4.8MB PNG, image/png
  • Org Limit: 10MB

Is there a hidden header requirement or a specific timeout on the upload URL that causes this? The docs are silent on pre-signed URL constraints.