Get 404 during websocket handshake with Azure SignalR Service

ZHANG Hao.h 25

I am using APIM as a reverse proxy in front of Azure SignalR service.

Everything looks good. The negotiate is successful and when it goes to the wss: API to build the connection it failed sometimes due to the handshake API return a 404 on signalR side. I can see that request on the SignalR live trace tool, it means the APIM does forward the handshake to signalR service, however sometimes it returns 404 instead of 101. Sometimes it works sometimes it doesn't. Any ideal why? The access_token is the same since I am using the same user to test it.
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ajkuma 22,851 Reputation points Microsoft Employee

2023-05-14T19:00:02.2333333+00:00

@ZHANG Hao.h ,

Just checking in to see if you had got a chance to see the previous response. If the answer helped (pointed you in the right direction) > please click Accept Answer Or please share the requested/more info to help you better.
ajkuma 22,851 Reputation points Microsoft Employee

2023-05-24T15:30:49.6533333+00:00

@ZHANG Hao.h , Kindly let us know the status of the issue. I'll follow-up further with you offline.
ZHANG Hao.h 25 Reputation points

2023-05-30T03:13:05.85+00:00

Any update on this?
ZHANG Hao.h 25 Reputation points

2023-05-30T03:16:32.3866667+00:00

It's still a problem. No clues why the request is failing, are you able to reproduce this?
ajkuma 22,851 Reputation points Microsoft Employee

2023-05-30T18:19:19.95+00:00

ZHANG Hao.h, Thanks for the follow-up. We wish to engage with you offline for a much closer look, please send an email with subject line “Attn:Ajay” to AzCommunity[at]Microsoft[dot]com with the following details, I will follow-up with you.

Referencing this thread,
Azure subscription ID,
WebApp name and the time of issue occurrence.

Much appreciate your cooperation!
ZHANG Hao.h 25 Reputation points

2023-05-31T03:08:48.1966667+00:00

I have sent you the email.
ajkuma 22,851 Reputation points Microsoft Employee

2023-06-01T13:29:01.2633333+00:00

As discussed, we have received the email and are working on this offline.

1 answer

ajkuma 22,851 Reputation points Microsoft Employee

2023-05-12T21:41:48.4166667+00:00
Apologies you are experiencing this issue. Kindly share more details about your app framework.

You may leverage Azure SignalR Services diagnostics from Azure Portal> Navigate to your ASignalR app in the Azure Portal. (screenshot below)

In the left navigation, click on Diagnose and solve problems - Review - “Resources Usage" and “Availability and Performance” options.

Typically, on ASP.net core, when using WebSockets and skipNegotiation = true

Please check these to isolate the issue:

When using multiple servers without sticky sessions, the connection can start on one server and then switch to another server. The other server is not aware of the previous connection.

Verify the client is connecting to the correct endpoint. For example, the server is hosted at http://127.0.0.1:5000/hub/myHub and client is trying to connect to http://127.0.0.1:5000/myHub.

If the connection uses the ID and takes too long to send a request to the server after the negotiate, the server:
- Deletes the ID. - Returns a 404.

Checkout this doc reference for more info: Troubleshoot connection errors

If the issue still persist, please check the logs to fetch more info

Logging and diagnostics in ASP.NET Core SignalR -- This article provides guidance for gathering diagnostics from your ASP.NET Core SignalR app to help troubleshoot issues.

Kindly let us know, I'll follow-up with you further.
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ZHANG Hao.h 25 Reputation points

2023-05-15T08:33:11.3+00:00

Thanks for your reply. I am using Azure SignalR service with serverless mode (With Azure function and got upstream endpoint configured).

I put an APIM in front of Azure SignalR service as reverse proxy. There are two APIs define in APIM for SignalR. One HTTP Post for Negotiate and one Websocket APIs for ws connection. And I use the React sdk on the client side, the negotiate request always return successfully, but the most of websocket API calls fail due to the handshake returning 404. like 3,4 out of 10 will return successfully(return 101).

I got the following request in the Live Trace Tool. Which means SignalR service received the handshake request and the url is correct. But this request sometime return 404 sometimes return 101. And the handshake happen right after the negotiate, so it's not like the same issue as your post.

I also enable Diagnose logs it shows the same thing as Live Trace Tool, it won't give any internal details why it return 404(connection deleted or something else?).

PS: When I connect without APIM, it is 100% successful.

My scenario is just a very simple one, to use APIM as reverse proxy for Negotiate and ws connection, according to the document it's supposed to work. Maybe you can recreate the issue on your side. Let me know if more info is needed.

ajkuma 22,851 Reputation points Microsoft Employee

2023-05-15T20:18:55.8366667+00:00

Thanks for the follow-up and additional info. I'm checking on this internally and will get back to you soon.

ajkuma 22,851 Reputation points Microsoft Employee

2023-05-17T19:15:09.3633333+00:00

While I'm checking on this internally, to keep you informed, for a deeper investigation on this we may need additional info about your subscription and resource, for which I'll follow-up offline.
Note: Kindly do not share any PII data on the public forum.

ajkuma 22,851 Reputation points Microsoft Employee

2023-06-05T19:10:13.5366667+00:00

To update:

To benefit the community find the right answer, posting our offline discussion.

Mitigated the issue by manually adding the extra slash on the “WebSocket URL” on Azure Portal.

It was identified with the request URL, after client, an extra ”/” must be added.
wss://test.service.signalr.net/client*/**?hub=&id=&access_token=_*
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Get 404 during websocket handshake with Azure SignalR Service

1 answer