Add troubleshooting page for SignalR by BrennanConroy · Pull Request #20125 · dotnet/AspNetCore.Docs

BrennanConroy · 2020-10-06T18:09:44Z

#20063

Needs some cleanup.

This is definitely missing some common scenarios. Don't need to get them all in this first pass.

bradygaster · 2020-10-06T18:22:04Z


-## Troubleshoot WebSocket handshake errors
-
-This section provides help on the *"Error during WebSocket handshake"* exception that occurs when trying to establish connection to ASP.NET Core SignalR hub.


Do we need quotes AND stars? One or the other seems like enough.

I deleted that 😛

bradygaster · 2020-10-06T18:22:44Z

+WebSocket connection to 'wss://xxx/HubName' failed: Error during WebSocket handshake: Unexpected response code: 404
+```
+
+* If the connection takes too long to send a request to the server after the negotiate the server will delete the ID and return a 404 if the connection uses that ID


Rick-Anderson

@FredHan001 FYI, this should hlep.

Rick-Anderson · 2020-10-06T19:43:11Z

@FredHan001 FYI

Co-authored-by: Rick Anderson <3605364+Rick-Anderson@users.noreply.github.com>

Rick-Anderson · 2020-10-10T03:59:22Z

@BrennanConroy let me know what's need to get this merged. Great info, thanks.

BrennanConroy · 2020-10-12T15:52:16Z

I guess it needs author to be filled in to get rid of the warnings

Rick-Anderson · 2020-10-12T18:18:48Z

halter73 · 2020-10-12T20:13:57Z

+* 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.


This is probably the least common cause of a 404, don't you think? I would probably order the bullet points with bad path first, no sticky session second and this last.

halter73 · 2020-10-12T20:17:20Z

+WebSocket connection to 'ws://xxx/HubName' failed: Error during WebSocket handshake: Unexpected response code: 307
+```
+
+This error can also happen during the negotiate request.


Do any of the HTTP clients and/or WebSocket clients SignalR uses not follow 307 redirects? I just searched the aspnetcore repo for "SignalR 307" (without quotes) and came up with no reports of an issue like that.

Found it: https://stackoverflow.com/questions/63437471/websocket-connection-to-ws-localhost5000-notificationhub-failed-error-duri. I'm still not sure that this could "happen during the negotiate request." Do you have evidence of that?

Yes, I point out one possible cause below

I don't see it. Why would a 307 break the negotiate request itself?

Because we don't follow redirects

Oh. Why? Because we assume it will break WebSockets?

Hmm, I'm not sure. I thought it was because auth handlers often redirect instead of returning 401, but we set a header to try and avoid that...

dotnet/aspnetcore#27068

Rick-Anderson · 2020-10-12T21:03:23Z

@Rick-Anderson I see your screenshot with the suggested pending changes to add @bradygaster as an author to this doc. Did you mean to submit a new review with those suggestion?

No, I made a bunch of suggestions, most were accepted. We can't merge this without the author meta-data. These are my suggestions, if you agree, I'll add them.

Rick-Anderson · 2020-10-14T18:16:35Z

The following needs to be added:

Q: Customer would like to know on the server the reason of the disconnection. However the exception parameter of the OnDisconnectedAsync seems to be always null:
public override async Task OnDisconnectedAsync(Exception exception)

A: I suspect you're right that there was some sort of network issue. If the connection closes between SignalR messages, the server may interpret that as an unexceptional client disconnect. I filed dotnet/aspnetcore#26701 to track the issue of not passing an Exception to Hub.OnDisconnectedAsync in this case.

Co-authored-by: Rick Anderson <3605364+Rick-Anderson@users.noreply.github.com>

BrennanConroy · 2020-10-20T17:20:43Z

The following needs to be added:

Q: Customer would like to know on the server the reason of the disconnection. However the exception parameter of the OnDisconnectedAsync seems to be always null:
public override async Task OnDisconnectedAsync(Exception exception)

A: I suspect you're right that there was some sort of network issue. If the connection closes between SignalR messages, the server may interpret that as an unexceptional client disconnect. I filed dotnet/aspnetcore#26701 to track the issue of not passing an Exception to Hub.OnDisconnectedAsync in this case.

I don't know what kind of wording we want in the doc for something like this.

bradygaster · 2020-10-20T18:24:28Z

Whilst not very friendly, I think the statement

If the connection closes between SignalR messages, the server may interpret that as an unexceptional client disconnect.

Sums it up concisely. That said, i'd love some wordsmithery by @Rick-Anderson

Rick-Anderson · 2020-10-20T19:13:57Z

If the connection closes between SignalR messages, the server may interpret that as an unexceptional client disconnect.

That's clear to me.

BrennanConroy · 2020-10-20T21:07:20Z

If the connection closes between SignalR messages, the server may interpret that as an unexceptional client disconnect.

That's clear to me.

Sure it's clear, but it doesn't mean anything. If we rephrase it a little it's equivalent to: "If the client closes the connection, it could be a graceful or ungraceful disconnect."

Rick-Anderson · 2020-10-20T21:13:09Z

@BrennanConroy I see your point. How about:

Transient network failures may close the connection between SignalR messages. The server may interpret the closed connection as an unexceptional client disconnect. For more information, see this GitHub issue.

Rick-Anderson · 2020-10-20T21:16:55Z

@BrennanConroy added
For more information, see this GitHub issue.

What I have is pretty incomplete, but the issue fleshes it out and we might get feedback on the issue.

Rick-Anderson · 2020-10-20T21:50:10Z

@BrennanConroy let me know when I can merge this.

BrennanConroy · 2020-10-20T23:47:26Z

Lets wait till middle of the day tomorrow to give folks some time to take a look

bradygaster · 2020-10-20T23:58:34Z

LGTM

BrennanConroy · 2020-10-21T22:48:38Z

Ok, think it's good to go

BrennanConroy added 2 commits October 6, 2020 10:33

Add troubleshooting page for SignalR

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BrennanConroy requested review from bradygaster, davidfowl and halter73 October 6, 2020 18:09

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Rick-Anderson merged commit 0622882 into master Oct 21, 2020

Rick-Anderson deleted the brecon/trouble branch October 21, 2020 23:46

BrennanConroy mentioned this pull request Oct 22, 2020

need a new page: "Troubleshooting connection issues" #20063

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		## Troubleshoot WebSocket handshake errors

		This section provides help on the "Error during WebSocket handshake" exception that occurs when trying to establish connection to ASP.NET Core SignalR hub.

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BrennanConroy commented Oct 6, 2020 •

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