I have configured a Collabora Online instance using Docker and integrated it with my ASP.NET Core (Blazor) application. The goal is to enable in-browser editing of Microsoft Word documents using Collabora via the WOPI protocol.
The backend WOPI endpoints are functioning correctly — I’m able to retrieve document metadata and content (e.g., /wopi/files/{id}, /wopi/files/{id}/contents) successfully via tools like Swagger or direct HTTP calls.
However, when attempting to load the document within the Collabora editor embedded in an <iframe> on the Blazor frontend, I receive the following error:
Unauthorized WOPI host. Please try again later and report to your administrator if the issue persists.
It seems the request reaches the Collabora instance, but fails due to WOPI host validation. The WOPISrc used in the iframe matches the backend host (e.g., http://localhost:5169/wopi/files/{id}), and I have added the relevant hostnames (localhost, host.docker.internal) to the <wopi> section in coolwsd.xml. SSL is also disabled via --o:ssl.enable=false.
What could be causing the WOPI host to be rejected despite being properly registered in coolwsd.xml, and how can I resolve this issue to allow document editing in the browser?
