Flutter Socket io Error on WebSocketException: Connection to was not upgraded to websocket

Question

I use this package and it work properly on test websites but in app I got this Error

WebSocketException: Connection to 'https://socket.excopro.com:0/socket.io/?EIO=3&transport=websocket#' was not upgraded to websocket

and this is my Code

SocketService() {
    var socket = io(
        'https://socket.excopro.com:443/', <String, dynamic>{
      'transports': ['websocket'],
      'autoConnect': true,
    });
    socket.on('connect', (_) {
      print('connect');
      socket.emit('msg', 'test');
    });
      socket.on("connecting", (data) => print('connecting'));
      socket.on('connect_error', (data) {
        print(data);
        socket.emit('msg', 'test');
      }); 
  }

I am facing similar issue. Any solution?

Sachin Tanpure
– Sachin Tanpure

2021-03-09 07:10:53 +00:00
Commented Mar 9, 2021 at 7:10 — Sachin Tanpure
– Sachin Tanpure, Commented Mar 9, 2021 at 7:10
Is it possible to print the error code somehow?

Mohammed Noureldin
– Mohammed Noureldin

2021-04-16 23:41:04 +00:00
Commented Apr 16, 2021 at 23:41 — Mohammed Noureldin
– Mohammed Noureldin, Commented Apr 16, 2021 at 23:41
@SachinTanpure delete / from end of url

Kanan
– Kanan

2024-02-21 12:44:36 +00:00
Commented Feb 21, 2024 at 12:44 — Kanan
– Kanan, Commented Feb 21, 2024 at 12:44

Sophanith Chhoun · Accepted Answer · 2021-04-10 03:21:18Z

9

I have met the same issue.

For my case, I use Nginx as proxy. I solve the issue by added some proxy header to my Nginx configuration.

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";

You can refer to this link.

answered Apr 10, 2021 at 3:21

Sophanith Chhoun

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3 Comments

Shajedul Islam Over a year ago

Hey how can i do that in shared cpanel/hosting

Matt Lampe Over a year ago

Thank you for this answer, I was having this issue running Bluebubbles client on Windows through my own nginx reverse proxy and this solved the problem for me.

Yusuf Over a year ago

hi, im currently facing this issue, please this proxy_set_header is it from the server side or the flutter side. thanks

DroidOS · Accepted Answer · 2021-05-21 13:12:39Z

3

I ran into this error in my Flutter/Dart app which is being serviced by NGinx + NChan. It turned out that the wss:... url that I was creating in Dart was malformed - easily done if you are doing string interpolation in Dart, PHP and JS all within the space of a few minutes given that each language has its own way of interpreting interpolated variables in braces. The result was that location = ~ /path/(regex)$ setting in my Nginx/NChan conf was not recognizing the URL as one that required upgrading to wss. Nginx then proceeded to try and find the resource at https://example.com/malformed/path without upgrading it to wss which then threw up this error in Dart.

Lesson - when this happens check that the URL you are trying to reach is well formed so it ends up being recognized as one requring an upgrade to wssserver side.

answered May 21, 2021 at 13:12

DroidOS

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2 Comments

Abhishek Mittal Over a year ago

Hey ! How to manage this String Interpolation from Flutter side ?

DroidOS Over a year ago

String interpolation in Dart is very similar to ES6. The only real difference is that Flutter does not require you to place variable values in braces most of the time. No harm if you do but usually your editor - I use VSCode - will warn you and even help you take them out. Dereferencing array variables with a variable index is, if I recall, one of the instances where you DO need to use braces

Hiran Walawage · Accepted Answer · 2022-01-01 11:18:45Z

You have make sure to enable websocket in Virtual Host.

RewriteCond %{HTTP:Upgrade} =websocket [NC]
RewriteCond %{HTTP:Connection} Upgrade [NC]
RewriteRule /(.*)           ws://127.0.0.1:3055/$1 [P,L]
RewriteCond %{HTTP:Upgrade} !=websocket [NC]
RewriteRule /(.*)           http://127.0.0.1:3055/$1 [P,L]

Here is the complete Virtual Host if anyone needs,

<VirtualHost *:80>
    ServerName domain.com
    ServerAlias www.domain.com

    ProxyRequests Off
    ProxyPreserveHost On
    ProxyVia Full

    <Proxy *>
        Require all granted
    </Proxy>

    ProxyPass / http://127.0.0.1:3055/
    ProxyPassReverse / https://127.0.0.1:3055/

    ProxyPass /api http://127.0.0.1:3055/api
    ProxyPassReverse /api https://127.0.0.1:3055/api

    RewriteEngine on

    RewriteCond %{HTTP:Upgrade} =websocket [NC]
    RewriteCond %{HTTP:Connection} Upgrade [NC]
    RewriteRule /(.*)           ws://127.0.0.1:3055/$1 [P,L]
    RewriteCond %{HTTP:Upgrade} !=websocket [NC]
    RewriteRule /(.*)           http://127.0.0.1:3055/$1 [P,L]

    RewriteCond %{SERVER_NAME} =domain.com [OR]
    RewriteCond %{SERVER_NAME} =www.domain.com
    RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
</VirtualHost>

rapaterno · Accepted Answer · 2022-02-04 08:24:52Z

1

Received this error when there was a mismatch on the client and server versions of socket_io. Try finding the matching version to the version the server is using.

answered Feb 4, 2022 at 8:24

rapaterno

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Comments

Stephen Ostermiller · Accepted Answer · 2022-05-07 11:06:17Z

1

I had for the same error, this is what my environment:

VPS with docker
Azuracast as container
Nginx proxy manager as container
a public domain that point to the Azuracast via hots in nginx proxy manager.
a flutter/dart mobile app that stream the radio flux, and I wanted to get "Now playing audio" updates via Websocket.

I had the same error when trying to connect via https schema with/without port.

I finally found that in nginx proxy manager I have to activate the Websocket option in the host I created. Then changed my url to wss://... instead of https://...

In flutter I used this package for websocket => web_socket_channel: ^2.2.0

and this is the line of code to init the websocket:

var websocket = IOWebSocketChannel.connect(Uri.parse('wss://xxx.com/api/live/nowplaying/my_station_shortcode'))

edited May 7, 2022 at 11:06

Stephen Ostermiller♦

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answered May 6, 2022 at 1:51

Nabil Ait Brahim

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Comments

Priyanshu Paliwal · Accepted Answer · 2025-04-03 11:03:30Z

1

I want having the same error,

my server socket_io version is 4.7.2

and I am using socket_io_client: ^3.1.1 in flutter

in my case CORS was causing the issue.

Try removing the CORS check from your socketio server.

answered Apr 3 at 11:03

Priyanshu Paliwal

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