WebSocket error after upgrade to XP7

Enonic version: 7.2.1
OS: Windows Server 2016 Datacenter

After using this server for months for hosting a XP6 site, we decided to reuse the server for a new XP7 site.

After a successful install of XP7 and a import of the data, I noticed that the website was not updating the “Mark as ready” and the “Publish”-button unless i refreshed the site.
I also noticed that after pressing publish, the loading bar would display, but would not go away without a refresh, even though the content was published.

After a dive into the developer console, I noticed that we were getting WebSocket errors:
_all.js:1 WebSocket connection to 'wss://XXXX.com/admin/event' failed: Error during WebSocket handshake: Incorrect 'Sec-WebSocket-Accept' header value

Our solution uses IIS as a reverse proxy and to encrypt the site using SSL.

To solve this, we had to ensure that the WebSocket feature was installed on IIS, which was done using this guide: https://docs.microsoft.com/en-us/iis/configuration/system.webserver/websocket


Actually, XP6 Admin also uses websockets, but perhaps not as intensively as XP7. Anyway, good catch!