SignalR IIS With React - "Server returned handshake error: Handshake was canceled."

user_9995089 0
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I am developing a .Net Core (3.1) web application hosted with IIS 10. When I am trying to use SignalR on localhost, I am able to connect totally fine and receive messages from the backend, but after I publish it to IIS, I get the error: "Server returned handshake error: Handshake was canceled." In the client logs on Chrome's console, I get the message: "Information: SSE connected to http://myserver.com/MyApplication/output" before I get the error described above (which you would think means that I connected successfully)...

I have seen other posts where people have suggested that I have to enable webSockets on IIS, and I have already checked the my site has this enabled.

I have also seen people suggest to try using the longPolling argument in the withUrl function when creating the connection, and this has not helped either.

I have also added SignalR Event Log Trace Listeners to my web.config file, and the only warning I get that might be related to this issue is that I get a warning from the .NET runtime that reads "Failed to determine the https port for redirect." I am not sure what this means or if it would be related to SignalR, but as this also appears to deal with Middleware, it might be significant.

One thing that I thought might be related is that my site is just one of multiple hosted on this server, so that when I am running locally, I can use the following to connect to SignalR:

hubConnection = new signalR.HubConnectionBuilder().withUrl("/output").build();

But because of the way this site is deployed on my server, I have to use this:

hubConnection = new signalR.HubConnectionBuilder().withUrl("/MyApplication/output").build();

when I deploy the site or else I get a 404 error...

Would there be any issue there? I noticed when inspecting the network requests that on localhost, the URL to connect with the socket is "wss://localhost:44315/output?id=..." and I get the "Status Code: 101 Switching Protocols", but after I deploy, the url that is used is "http://myserver.com/MyApplication/output?id=..." and I get a "200 OK" just before receiving the error described at the top. Why does wss get used on localhost but http is requested from my client when I deploy?

signalr asp.net-core reactjs iis
1 Answers

FINALLY discovered the issue after days of debugging... The reason I was getting a "101" response on localhost and not when published is because 101 is basically the server (IIS in my case) saying "I support web sockets". I realized that because I wasn't getting this when published, web sockets were probably not enabled in IIS. It was weird, however, because I went into IIS manager and it said that web sockets were enabled, but after much more research, I found that you also have to go into "Server Manager" and enable it as well (see here https://docs.microsoft.com/en-us/iis/get-started/whats-new-in-iis-8/iis-80-websocket-protocol-support and follow step by step instructions). I did not realize both were required.

user_99950890
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