How do I debug error ECONNRESET in Node js

Question

I m running an Express js application using Socket io for a chat webapp and I get the following error randomly around 5 times during 24h  The node process is wrapped in forever and it restarts itself immediately   The problem is that restarting Express kicks my users out of their rooms  and nobody wants that   The web server is proxied by HAProxy  There are no socket stability issues   just using websockets and flashsockets transports  I cannot reproduce this on purpose   This is the error with Node v0 10 11       events js 72             throw er     Unhandled  error  event                         Error  read ECONNRESET       alternatively it s a  write          at errnoException  net js 900 11          at TCP onread  net js 555 19      error  Forever detected script exited with code  8     error  Forever restarting script for 2 time   EDIT  2013-07-22   Added both socket io client error handler and the uncaught exception handler  Seems that this one catches the error       process on  uncaughtException   function  err          console error err stack         console log  Node NOT Exiting                 So I suspect it s not a Socket io issue but an HTTP request to another server  that I do or a MySQL Redis connection  The problem is that the error stack  doesn t help me identify my code issue  Here is the log output       Error  read ECONNRESET         at errnoException  net js 900 11          at TCP onread  net js 555 19    How do I know what causes this  How do I get more out of the error   Ok  not very verbose but here s the stacktrace with Longjohn       Exception caught  Error ECONNRESET        Error  read ECONNRESET        code   ECONNRESET         errno   ECONNRESET         syscall   read           cached trace               receiver   Object              fun   Function  errnoException              pos  22930               receiver   Object   fun   Function  onread   pos  14545                            receiver   Object              fun   Function  fireErrorCallbacks              pos  11672               receiver   Object   fun   Function   pos  12329               receiver   Object   fun   Function  onread   pos  14536              previous              Error           id  1061835           location   fireErrorCallbacks  net js 439               location     process nextTick              previous    null             trace count    1             cached trace       Object    Object    Object          Here I serve the flash socket policy file       net   require  net       net createServer   socket    gt        socket write   lt  xml version   1 0    gt  n         socket write   lt  DOCTYPE cross-domain-policy SYSTEM   http   www macromedia com xml dtds cross-domain-policy dtd   gt  n         socket write   lt cross-domain-policy gt  n         socket write   lt allow-access-from domain       to-ports        gt  n         socket write   lt  cross-domain-policy gt  n         socket end         listen 843    Can this be the cause

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I was facing the same issue but I mitigated it by placing   server timeout   0    before server listen  server is an HTTP server here  The default timeout is 2 minutes as per the API documentation

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A simple tcp server I had for serving the flash policy file was causing this  I can now catch the error using a handler     serving the flash policy file net   require  net    net createServer  socket    gt      just added   socket on  error    err    gt      console log  Caught flash policy server socket error         console log err stack         socket write   lt  xml version   1 0    gt  n     socket write   lt  DOCTYPE cross-domain-policy SYSTEM   http   www macromedia com xml dtds cross-domain-policy dtd   gt  n     socket write   lt cross-domain-policy gt  n     socket write   lt allow-access-from domain       to-ports        gt  n     socket write   lt  cross-domain-policy gt  n     socket end     listen 843

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I also get ECONNRESET error during my development  the way I solve it is by not using nodemon to start my server  just use  node server js  to start my server fixed my problem    It s weird  but it worked for me  now I never see the ECONNRESET error again

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I had a similar problem where apps started erroring out after an upgrade of Node   I believe this can be traced back to Node release v0 9 10 this item    net  don t suppress ECONNRESET  Ben Noordhuis    Previous versions wouldn t error out on interruptions from the client   A break in the connection from the client throws the error ECONNRESET in Node   I believe this is intended functionality for Node  so the fix  at least for me  was to handle the error  which I believe you did in unCaught exceptions   Although I handle it in the net socket handler   You can demonstrate this   Make a simple socket server and get Node v0 9 9 and v0 9 10   require  net        createServer  function socket                       no nothing             listen 21  function                     console log  Socket ON            Start it up using v0 9 9 and then attempt to FTP to this server  I m using FTP and port 21 only because I m on Windows and have an FTP client  but no telnet client handy    Then from the client side  just break the connection   I m just doing Ctrl-C   You should see NO ERROR when using Node v0 9 9  and ERROR when using Node v 0 9 10 and up   In production  I use v 0 10  something and it still gives the error  Again  I think this is intended and the solution is to handle the error in your code

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Try adding these options to socket io   const options     transports    websocket    pingTimeout  3000  pingInterval  5000      I hope this will help you

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I solved the problem by simply connecting to a different network  That is one of the possible problems   As discussed above  ECONNRESET means that the TCP conversation abruptly closed its end of the connection    Your internet connection might be blocking you from connecting to some servers  In my case  I was trying to connect to mLab   cloud database service that hosts MongoDB databases   And my ISP is blocking it

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I had this Error too and was able to solve it after days of debugging and analysis   my solution  For me VirtualBox  for Docker  was the Problem  I had Port Forwarding configured on my VM and the error only occured on the forwarded port   general conclusions  The following observations may save you days of work I had to invest    For me the problem only occurred on connections from localhost to localhost on one port  -  check changing any of these constants solves the problem  For me the problem only occurred on my machine -  let someone else try it  For me the problem only occurred after a while and couldn t be reproduced reliably My Problem couldn t be inspected with any of nodes or expresses  debug- tools  -  don t waste time on this   -  figure out if something is messing around with your network  -settings   like VMs  Firewalls etc   this is probably the cause of the problem

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Another possible case  but rare  could be if you have server to server communications and have set server maxConnections to a very low value   In node s core lib net js it will call clientHandle close   which will also cause error ECONNRESET   if  self maxConnections  amp  amp  self  connections  gt   self maxConnections      clientHandle close       causes ECONNRESET on the other end   return

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I had the same issue and it appears that the Node js version was the problem   I installed the previous version of Node js  10 14 2  and everything was ok using nvm  allow you to install several version of Node js and quickly switch from a version to another    It is not a  clean  solution  but it can serve you temporarly

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I had resolved this problem by    Turning off my wifi ethernet connection and turn on   I typed  npm update in terminal to update npm  I tried to log out from the session and log in again   After that I tried the same npm command and the good thing was it worked out  I wasn t sure it is that simple   I am using CENTOS 7

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You might have guessed it already  it s a connection error      ECONNRESET  means the other side of the TCP conversation abruptly closed its end of the connection  This is most probably due to one or more application protocol errors  You could look at the API server logs to see if it complains about something   But since you are also looking for a way to check the error and potentially debug the problem  you should take a look at  How to debug a socket hang up error in NodeJS   which was posted at stackoverflow in relation to an alike question      Quick and dirty solution for development       Use  longjohn  you get long stack traces that will contain the async operations       Clean and correct solution      Technically  in node  whenever you emit an  error  event and no one listens to it  it will throw  To make it not throw  put a listener on it and handle  it yourself  That way you can log the error with more information       To have one listener for a group of calls you can use domains  and also catch other errors on runtime  Make sure each async operation related to http Server Client  is in different domain context comparing to the other parts of the code  the domain will automatically listen to the error events and will propagate it to it s own handler  So you only listen to that handler and get the error data  You also get more information for free    EDIT  2013-07-22   As I wrote above        ECONNRESET  means the other side of the TCP conversation abruptly closed its end of the connection  This is most probably due to one or more application protocol errors  You could look at the API server logs to see if it complains about something    What could also be the case  at random times  the other side is overloaded and simply kills the connection as a result  If that s the case  depends on what you re connecting to exactly     But one thing s for sure  you indeed have a read error on your TCP connection which causes the exception  You can see that by looking at the error code you posted in your edit  which confirms it

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I just figured this out  at least in my use case   I was getting ECONNRESET  It turned out that the way my client was set up  it was hitting the server with an API call a ton of times really quickly -- and it only needed to hit the endpoint once    When I fixed that  the error was gone

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Yes  your serving of the policy file can definitely cause the crash  To repeat  just add a delay to your code  net createServer  function socket         for  i 0  i lt 1000000000  i          socket write  quot  lt  xml version   quot 1 0  quot   gt  n quot             and use telnet to connect to the port  If you disconnect telnet before the delay has expired  you ll get a crash  uncaught exception  when socket write throws an error  To avoid the crash here  just add an error handler before reading writing the socket  net createServer function socket        for i 0  i lt 1000000000  i         socket on  error   function error    console error  quot error quot   error           socket write  quot  lt  xml version   quot 1 0  quot   gt  n quot       When you try the above disconnect  you ll just get a log message instead of a crash  And when you re done  remember to remove the delay

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Had the same problem today  After some research i found a very useful --abort-on-uncaught-exception node js option  Not only it provides much more verbose and useful error stack trace  but also saves core file on application crash allowing further debug

[node.js] How do I debug error ECONNRESET in Node.js?

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