Unable to connect to the server with any of the available transports.

[alexfdezsauco]

After the update to the latest version 0.12.0-blazor-3.1.0-preview3.19555.2 I'm not able to connect to the server.

The call to StartAsync throws System.InvalidOperationException

WASM: System.InvalidOperationException: Unable to connect to the server with any of the available transports.

Server logs:

[09:42:55 DBG] Request matched endpoint '/hubs/messages/negotiate'
[09:42:55 INF] Authorization was successful.
[09:42:55 INF] Executing endpoint '/hubs/messages/negotiate'
[09:42:55 DBG] New connection FavukK3OysTrusvbxCY51w created.
[09:42:55 DBG] Sending negotiation response.
[09:42:55 DBG] The response will be compressed with 'gzip'.
[09:42:55 INF] Executed endpoint '/hubs/messages/negotiate'
[09:42:55 INF] HTTP POST /hubs/messages/negotiate responded 200 in 58.2895 ms
[09:42:55 DBG] Connection id "0HLSBK3GB4LE6" completed keep alive response.
[09:42:55 INF] Request finished in 78.6788ms 200 application/json

[alexfdezsauco]

Workaround: Set Transport to HttpTransportType.LongPolling.

Since Server Side Events and Web Sockets are Implemented in Java Script this could be related with the way to include the static assets (JavaScript file).

[gdar91]

I have found, there is no way to include the javascript file that initializes the library. If you go to the source, you can find an assembly named "BlazorSignalR.JS" that seems to be responsible for building the js file for interop, but, as I have checked multiple times, there is no use of it. Or you have to manually copy and build the file into your wwwroot directory and reference it from your index.html.