Our admin print action extension broke after upgrading to 2025-10 and Preact. The PDF loads fine when we open the URL directly, but in Shopify admin we get "This content is blocked. Contact the site owner to fix the issue."
We've added CORS headers and confirmed the route returns the right Content-Type. The PDF works in the browser but not in the admin preview.
We're using:
- API 2025-10
- Preact extension
- admin.order-index.selection-print-action.render target
- Gadget HTTP route returning application/pdf
The route has Access-Control-Allow-Origin: * and Content-Type: application/pdf. We've tried both the app: protocol and full URLs.
Has anyone got PDFs working in admin print actions with 2025-10? Are we missing headers or CSP settings?