WebSocket connection failed Error during WebSocket handshake Unexpected response code 400

Question

I am trying to integrate Socket io with Angular and I m having difficulties making a connection from the client-side to the server  I ve looked through other related questions but my issue is happening locally  so there s no web server in the middle   This is what my server code looks like   const app   express    const server   http createServer app   const io   require  socket io   listen server    io on  connection   function socket      socket emit  greet     hello   Hey  Mr Client          socket on  respond   function data        console log data           socket on  disconnect   function         console log  Socket disconnected                I m loading the client side JavaScript files using Grunt in the following order   dist        src            public bower components angular angular min js                      public bower components socket io-client dist socket io min js          public bower components angular-socket-io socket min js                        Then in my controller   function MyController  scope         let socket   io connect window location href       socket connect  http   localhost 3000        socket on  greet   function data          console log data         socket emit  respond     message   Hello to you too  Mr Server                            Before actually using the btford angular-socket-io library  I want to make sure that I can get a connection correctly  but I get the following error in the console     The interesting thing is that if I restart the Node js server process  it does manage to send the message but using polling instead of websockets       I tried all sorts of different options in the socket connect call  but nothing worked   Any help would be appreciated     UPDATE  30 12 2016    I just realized that websockets is working partially  I see a 101 Switching Protocols request in the Chrome developer console  However the only frames I see there are the engine io protocol packets  ping  pong   However my application socket messages still fall back to polling for some reason

User · Answer

I solved this by changing transports from  websocket  to  polling      var socket   io connect  xxx xxx xxx xxx 8000           transports    polling

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Had the same issue  my app is behind nginx  Making these changes to my Nginx config removed the error  location     proxy pass http   localhost 8080  proxy http version 1 1  proxy set header Upgrade  http upgrade  proxy set header Connection  quot upgrade quot   proxy set header Host  host

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The currently accepted solution is misleading  According to the official documentation  adding the transports     websocket    option effectively removes the ability to fallback to long-polling when the websocket connection cannot be established  This option is what makes socket io so robust in the first place because it can adapt to many scenarios  In that particular case where one wishes to solely rely on websockets  directly using the WebSocket API is recommended  For other cases  supposedly most users   this is most likely a reverse proxy server configuration problem  The official documentation suggests the following depending on your environment  NginX configuration http     server       listen 3000      server name io yourhost com       location           proxy set header X-Forwarded-For  proxy add x forwarded for        proxy set header Host  host         proxy pass http   nodes           enable WebSockets       proxy http version 1 1        proxy set header Upgrade  http upgrade        proxy set header Connection  quot upgrade quot                upstream nodes         enable sticky session based on IP     ip hash       server app01 3000      server app02 3000      server app03 3000         Apache HTTPD configuration Header add Set-Cookie  quot SERVERID sticky   BALANCER WORKER ROUTE e  path   quot  env BALANCER ROUTE CHANGED   lt Proxy  quot balancer   nodes polling quot  gt      BalancerMember  quot http   app01 3000 quot  route app01     BalancerMember  quot http   app02 3000 quot  route app02     BalancerMember  quot http   app03 3000 quot  route app03     ProxySet stickysession SERVERID  lt  Proxy gt    lt Proxy  quot balancer   nodes ws quot  gt      BalancerMember  quot ws   app01 3000 quot  route app01     BalancerMember  quot ws   app02 3000 quot  route app02     BalancerMember  quot ws   app03 3000 quot  route app03     ProxySet stickysession SERVERID  lt  Proxy gt   RewriteEngine On RewriteCond   HTTP Upgrade   websocket  NC  RewriteRule       balancer   nodes ws  1  P L  RewriteCond   HTTP Upgrade    websocket  NC  RewriteRule       balancer   nodes polling  1  P L   ProxyTimeout 3  HAProxy configuration listen chat   bind   80   default backend nodes  backend nodes   option httpchk HEAD  health   http-check expect status 200   cookie io prefix indirect nocache   using the  io  cookie set upon handshake   server app01 app01 3000 check cookie app01   server app02 app02 3000 check cookie app02   server app03 app03 3000 check cookie app03  Also worth reading this on upgrading connections in HAProxy  For more details please refer to the official documentation link above  EDIT  Varnish  source here  sub vcl recv       if  req http upgrade    quot   i websocket quot             return  pipe            sub vcl pipe       if  req http upgrade            set bereq http upgrade   req http upgrade          set bereq http connection   req http connection

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In my case  I have just install express-status-monitor to get rid of this error here are the settings install express-status-monitor npm i express-status-monitor --save const expressStatusMonitor   require  express-status-monitor    app use expressStatusMonitor       websocket  io      port  app get  port

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Problem solved  I just figured out how to solve the issue  but I would still like to know if this is normal behavior or not   It seems that even though the Websocket connection establishes correctly  indicated by the 101 Switching Protocols request   it still defaults to long-polling  The fix was as simple as adding this option to the Socket io connection function    transports    websocket      So the code finally looks like this   const app   express    const server   http createServer app   var io   require  socket io   server    io on  connection   function socket      console log  connected socket        socket on  greet   function data        console log data       socket emit  respond     hello   Hey  Mr Client               socket on  disconnect   function         console log  Socket disconnected                and on the client   var socket   io  ws   localhost 3000    transports    websocket      socket on  connect   function        console log  connected       socket emit  greet     message   Hello Mr Server            socket on  respond   function  data      console log data         And the messages now appear as frames   working websockets  This Github issue pointed me in the right direction  Thanks to everyone who helped out

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In your controller  you are using an http scheme  but I think you should be using a ws scheme  as you are using websockets  Try to use ws   localhost 3000 in your connect function

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Using Apollo Server 2  Per https   github com apollographql apollo-client issues 4778 issuecomment-509638071  this solved my problem   try  ws   localhost 4000 graphql      since incoming and outgoing requests now use the same address

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After using following load balancer setting my problem solved for wss but for ws problem still exists for specific one ISP   calssic-load-balancer

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if you are using httpd apache  you can add a file something like ws conf and add this code to it  Also  this solution can proxy something like this  quot http   localhost 6001 socket io quot  to just this  quot http   localhost socket io quot   lt VirtualHost   80 gt      RewriteEngine on       redirect WebSocket     RewriteCond   REQUEST URI     socket io             NC      RewriteCond   QUERY STRING  transport websocket     NC      RewriteRule                 ws   localhost 6001  1  P L       ProxyPass         socket io http   localhost 6001 socket io     ProxyPassReverse  socket io http   localhost 6001 socket io  lt  VirtualHost gt

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This worked for me with Nginx  Node server and Angular 4  Edit your nginx web server config file as   server   listen 80  server name 52 xx xxx xx   location         proxy set header   X-Forwarded-For  remote addr      proxy set header   Host  http host      proxy pass          http   127 0 0 1 4200       proxy http version 1 1      proxy set header   Upgrade  http upgrade      proxy set header   Connection  upgrade

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Judging from the messages you send via Socket IO socket emit  greet     hello   Hey  Mr Client        it seems that you are using the hackathon-starter boilerplate  If so  the issue might be that express-status-monitor module is creating its own socket io instance  as per  https   github com RafalWilinski express-status-monitor using-module-with-socketio-in-project  You can either    Remove that module Pass in your socket io instance and port as websocket when you create the expressStatusMonitor instance like below   const server   require  http   Server app   const io   require  socket io   server       app use expressStatusMonitor   websocket  io  port  app get  port

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The problem for me was not got the port from process env PORT it is very important because Heroku and other services properly do a random port numbers to use  So that is the code that work for me eventuly   var app   require  express      var http   require  http   createServer app   const serverPort   process env PORT      lt ----- important   const io   require  socket io   http     cors        origin           methods   GET PUT POST DELETE OPTIONS  split           credentials  true          http listen serverPort     gt     console log  server listening on port   serverPort

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I think you should define your origins for client side as bellow    x000D   x000D    server js x000D  const socket   require  socket io    x000D  const app   require  express      x000D  const server   app listen  port    x000D   x000D  const io   socket   attach server   x000D  io origins  your domain port www your domain port your IP port your domain     x000D   x000D  io on  connection    socket    gt    x000D    console log  connected a new client    x000D      x000D   x000D    client js x000D  var socket   io  ws    port    x000D   x000D   x000D

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You re using port 3000 on the client-side  I d hazard a guess that s the Angular port and not the server port  It should be connecting to the server port

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I had faced same issues  I refined apache2 virtual host entery and got success   Note  on server I had succesful installed and working on 9001 port without any issue  This guide line for apache2 only no relavence with nginx  this answer for apache2 etherpad lovers    lt VirtualHost   80 gt    ServerName pad tejastank com   ServerAlias pad tejastank com   ServerAdmin snippetbucket gmail com    LoadModule  proxy module          usr lib apache2 modules mod proxy so   LoadModule  proxy http module     usr lib apache2 modules mod proxy http so   LoadModule  headers module        usr lib apache2 modules mod headers so   LoadModule  deflate module        usr lib apache2 modules mod deflate so    ProxyVia On   ProxyRequests Off   ProxyPreserveHost on       lt Location   gt          ProxyPass http   localhost 9001  retry 0 timeout 30         ProxyPassReverse http   localhost 9001       lt  Location gt       lt Location  socket io gt            This is needed to handle the websocket transport through the proxy  since           etherpad does not use a specific sub-folder  such as  ws  to handle this kind of traffic            Taken from https   github com ether etherpad-lite issues 2318 issuecomment-63548542           Thanks to beaugunderson for the semantics         RewriteEngine On         RewriteCond   QUERY STRING  transport websocket     NC          RewriteRule       ws   localhost 9001 socket io  1  P L          ProxyPass http   localhost 9001 socket io retry 0 timeout 30         ProxyPassReverse http   localhost 9001 socket io      lt  Location gt       lt Proxy   gt      Options FollowSymLinks MultiViews     AllowOverride All     Order allow deny     allow from all    lt  Proxy gt   lt  VirtualHost gt    Advance tips  Please with help of a2enmod enable all mod of apache2  Restart apache2 than will get effect  But obvious a2ensite to enable site required

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I solved this by removing io listen server    I started running into this error when I started integrating passport socketio and using passport middleware

[javascript] WebSocket connection failed: Error during WebSocket handshake: Unexpected response code: 400

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