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Can't set headers after they are sent #930

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xolf opened this issue Dec 27, 2015 · 6 comments
Closed

Can't set headers after they are sent #930

xolf opened this issue Dec 27, 2015 · 6 comments

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@xolf
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xolf commented Dec 27, 2015

I just got a very strange error. The proxy tries to send the header twice and I have no idea why.

_http_outgoing.js:335
    throw new Error('Can\'t set headers after they are sent.');
          ^
Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:335:11)
    at g:\nodejs\http-proxy\node_modules\http-proxy\lib\http-proxy\passes\web-outgoing.js:85:11
    at Array.forEach (native)
    at Array.writeHeaders (g:\nodejs\http-proxy\node_modules\http-proxy\lib\http-proxy\passes\web-outgoing.js:84:35)
    at ClientRequest.<anonymous> (g:\nodejs\http-proxy\node_modules\http-proxy\lib\http-proxy\passes\web-incoming.js:151:20)
    at ClientRequest.emit (events.js:107:17)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:419:21)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:111:23)
    at Socket.socketOnData (_http_client.js:310:20)
    at Socket.emit (events.js:107:17)

My proxy.js file: https://gist.github.com/xolf/f79a1f939d7dc64c9894
@adambiggs
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+1 I'm having the same problem.

@pyper
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pyper commented Jan 5, 2016

This situation happens when request() call throws an error. It looks like you have a race condition between your response error function and the web proxy. What is happening is the request() call is failing and the custom error handler and the proxy are fighting over the same response object. res.headersSent will not provide you protection because after both times you use them there is many asynchronous callbacks past them. The stack trace I am getting is indicating the error is originating in the proxy which mean the header flush was likely triggered by res.end() on line 31. This f’d up the proxy since it can no longer write headers itself because the headers were sent there. You have to rethink the fundamental structure of this app to account for the for asynchronous nature of node and http-proxy.

@jasonniebauer
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+1 I'm having the same problem

@xolf
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xolf commented Mar 9, 2016

Is there a way to ignore this error and force the server keep on running?

@bubenshchykov
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+1

@rick-kilgore rick-kilgore mentioned this issue Nov 14, 2016
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@gabrielmancini
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+1

thiagobustamante added a commit to thiagobustamante/node-http-proxy that referenced this issue May 26, 2017
@thiagobustamante
Fix "Can't set headers after they are sent" errors
ebd795c 
This PR tries to fix "Can't set headers after they are sent" errors.
That are a lot of situations where this error can occurs. In my case, it is happening because I have others middlewares (in an expressjs application that tries to proxy requests). Some of those middlewares (like [passportjs](http://passportjs.org/), or [cors](https://www.npmjs.com/package/cors)) can run ```res.end()``` and when the proxy receive a response, it is already finished.
So, it is necessary to test if we can write on the user response when the proxy response is ready.
I think it could also fix http-party#930, http-party#1168, http-party#908
@thiagobustamante thiagobustamante mentioned this issue May 26, 2017
Closed
@xolf xolf closed this as completed Apr 11, 2018
jcrugzz pushed a commit that referenced this issue Apr 19, 2018
@thiagobustamante @jcrugzz
Fix "Can't set headers after they are sent" errors
c611484 
This PR tries to fix "Can't set headers after they are sent" errors.
That are a lot of situations where this error can occurs. In my case, it is happening because I have others middlewares (in an expressjs application that tries to proxy requests). Some of those middlewares (like [passportjs](http://passportjs.org/), or [cors](https://www.npmjs.com/package/cors)) can run ```res.end()``` and when the proxy receive a response, it is already finished.
So, it is necessary to test if we can write on the user response when the proxy response is ready.
I think it could also fix #930, #1168, #908
jcrugzz pushed a commit that referenced this issue Apr 20, 2018
@thiagobustamante @jcrugzz
Fix "Can't set headers after they are sent" errors
b0a4489 
This PR tries to fix "Can't set headers after they are sent" errors.
That are a lot of situations where this error can occurs. In my case, it is happening because I have others middlewares (in an expressjs application that tries to proxy requests). Some of those middlewares (like [passportjs](http://passportjs.org/), or [cors](https://www.npmjs.com/package/cors)) can run ```res.end()``` and when the proxy receive a response, it is already finished.
So, it is necessary to test if we can write on the user response when the proxy response is ready.
I think it could also fix #930, #1168, #908
indexzero pushed a commit that referenced this issue Apr 20, 2018
@thiagobustamante @indexzero
Fix "Can't set headers after they are sent" errors
8097ae2 
This PR tries to fix "Can't set headers after they are sent" errors.
That are a lot of situations where this error can occurs. In my case, it is happening because I have others middlewares (in an expressjs application that tries to proxy requests). Some of those middlewares (like [passportjs](http://passportjs.org/), or [cors](https://www.npmjs.com/package/cors)) can run ```res.end()``` and when the proxy receive a response, it is already finished.
So, it is necessary to test if we can write on the user response when the proxy response is ready.
I think it could also fix #930, #1168, #908
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Fix "Can't set headers after they are sent" errors thiagobustamante/node-http-proxy
6 participants
@pyper @gabrielmancini @adambiggs @bubenshchykov @jasonniebauer @xolf