Web Messaging file upload 413 errors despite small file size

We are configuring file upload limits for Web Messaging via the Genesys Cloud API. The goal is to restrict uploads to specific MIME types and enforce a 5MB cap. We have updated the channel configuration using a Terraform module, but customers still receive 413 errors when uploading images under the limit. The API documentation is vague on where these limits are enforced in the SDK. Is there a specific endpoint for validating MIME types before the upload attempt? We have tried the following steps:

  • Set max_file_size to 5242880 in the channel config.
  • Verified allowed MIME types in the settings JSON.
  • Checked browser console for network errors.

The upload fails immediately without reaching the server.