15 Common Error Codes in Node.js and How to Fix Them | Better Stack Community (2023)

You will encounter various kinds of errors while developing Node.jsapplications, but most can be avoided or easily mitigated with the right codingpractices. However, most of the information to fix these problems are currentlyscattered across various GitHub issues and forum posts which could lead tospending more time than necessary when seeking solutions.

Therefore, we've compiled this list of 15 common Node.js errors along with oneor more strategies to follow to fix each one. While this is not a comprehensivelist of all the errors you can encounter when developing Node.js applications,it should help you understand why some of these common errors occur and feasiblesolutions to avoid future recurrence.

1. ECONNRESET

ECONNRESET is a common exception that occurs when the TCP connection toanother server is closed abruptly, usually before a response is received. It canbe emitted when you attempt a request through a TCP connection that has alreadybeen closed or when the connection is closed before a response is received(perhaps in case of a timeout). This exception will usuallylook like the following depending on your version of Node.js:

Error: socket hang up at connResetException (node:internal/errors:691:14) at Socket.socketOnEnd (node:_http_client:466:23) at Socket.emit (node:events:532:35) at endReadableNT (node:internal/streams/readable:1346:12) at processTicksAndRejections (node:internal/process/task_queues:83:21) { code: 'ECONNRESET'}

If this exception occurs when making a request to another server, you shouldcatch it and decide how to handle it. For example, you can retry the requestimmediately, or queue it for later. You can also investigate your timeoutsettings if you'd like to wait longer for the request to becompleted.

On the other hand, if it is caused by a client deliberately closing anunfulfilled request to your server, then you don't need to do anything exceptend the connection (res.end()), and stop any operations performed ingenerating a response. You can detect if a client socket was destroyed throughthe following:

app.get("/", (req, res) => { // listen for the 'close' event on the request req.on("close", () => { console.log("closed connection"); }); console.log(res.socket.destroyed); // true if socket is closed});

2. ENOTFOUND

The ENOTFOUND exception occurs in Node.js when a connection cannot beestablished to some host due to a DNS error. This usually occurs due to anincorrect host value, or when localhost is not mapped correctly to127.0.0.1. It can also occur when a domain goes down or no longer exists.Here's an example of how the error often appears in the Node.js console:

Error: getaddrinfo ENOTFOUND http://localhost at GetAddrInfoReqWrap.onlookup [as oncomplete] (node:dns:71:26) { errno: -3008, code: 'ENOTFOUND', syscall: 'getaddrinfo', hostname: 'http://localhost'}

If you get this error in your Node.js application or while running a script, youcan try the following strategies to fix it:

Check the domain name

First, ensure that you didn't make a typo while entering the domain name. Youcan also use a tool like DNS Checker to confirm thatthe domain is resolving successfully in your location or region.

Check the host value

If you're using http.request() or https.request() methods from the standardlibrary, ensure that the host value in the options object contains only thedomain name or IP address of the server. It shouldn't contain the protocol,port, or request path (use the protocol, port, and path properties forthose values respectively).

// don't do thisconst options = { host: 'http://example.com/path/to/resource',};// do this insteadconst options = { host: 'example.com', path: '/path/to/resource',};http.request(options, (res) => {});

Check your localhost mapping

If you're trying to connect to localhost, and the ENOTFOUND error is thrown,it may mean that the localhost is missing in your hosts file. On Linux andmacOS, ensure that your /etc/hosts file contains the following entry:

127.0.0.1 localhost

You may need to flush your DNS cache afterward:

sudo killall -HUP mDNSResponder # macOS

On Linux, clearing the DNS cache depends on the distribution and caching servicein use. Therefore, do investigate the appropriate command to run on your system.

3. ETIMEDOUT

The ETIMEDOUT error is thrown by the Node.js runtime when a connection or HTTPrequest is not closed properly after some time. You might encounter this errorfrom time to time if you configured a timeout on youroutgoing HTTP requests. The general solution to this issue is to catch the errorand repeat the request, preferably using anexponential backoffstrategy so that a waiting period is added between subsequent retries until therequest eventually succeeds, or the maximum amount of retries is reached. If youencounter this error frequently, try to investigate your request timeoutsettings and choose a more appropriate value for the endpointif possible.

4. ECONNREFUSED

The ECONNREFUSED error is produced when a request is made to an endpoint but aconnection could not be established because the specified address wasn'treachable. This is usually caused by an inactive target service. For example,the error below resulted from attempting to connect to http://localhost:8000when no program is listening at that endpoint.

Error: connect ECONNREFUSED 127.0.0.1:8000 at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1157:16)Emitted 'error' event on ClientRequest instance at: at Socket.socketErrorListener (node:_http_client:442:9) at Socket.emit (node:events:526:28) at emitErrorNT (node:internal/streams/destroy:157:8) at emitErrorCloseNT (node:internal/streams/destroy:122:3) at processTicksAndRejections (node:internal/process/task_queues:83:21) { errno: -111, code: 'ECONNREFUSED', syscall: 'connect', address: '127.0.0.1', port: 8000}

The fix for this problem is to ensure that the target service is active andaccepting connections at the specified endpoint.

5. ERRADDRINUSE

This error is commonly encountered when starting or restarting a web server. Itindicates that the server is attempting to listen for connections at a port thatis already occupied by some other application.

Error: listen EADDRINUSE: address already in use :::3001 at Server.setupListenHandle [as _listen2] (node:net:1330:16) at listenInCluster (node:net:1378:12) at Server.listen (node:net:1465:7) at Function.listen (/home/ayo/dev/demo/node_modules/express/lib/application.js:618:24) at Object.<anonymous> (/home/ayo/dev/demo/main.js:16:18) at Module._compile (node:internal/modules/cjs/loader:1103:14) at Object.Module._extensions..js (node:internal/modules/cjs/loader:1157:10) at Module.load (node:internal/modules/cjs/loader:981:32) at Function.Module._load (node:internal/modules/cjs/loader:822:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12)Emitted 'error' event on Server instance at: at emitErrorNT (node:net:1357:8) at processTicksAndRejections (node:internal/process/task_queues:83:21) { code: 'EADDRINUSE', errno: -98, syscall: 'listen', address: '::', port: 3001}

The easiest fix for this error would be to configure your application to listenon a different port (preferably by updating an environmental variable). However,if you need that specific port that is in use, you can find out the process IDof the application using it through the command below:

lsof -i tcp:3000

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAMEnode 2902 ayo 19u IPv6 781904 0t0 TCP *:3001 (LISTEN)

Afterward, kill the process by passing the PID value to the kill command:

kill -9 2902

After running the command above, the application will be forcefully closedfreeing up the desired port for your intended use.

6. EADDRNOTAVAIL

This error is similar to EADDRINUSE because it results from trying to run aNode.js server at a specific port. It usually indicates a configuration issuewith your IP address, such as when you try to bind your server to a static IP:

const express = require('express');const app = express();const server = app.listen(3000, '192.168.0.101', function () { console.log('server listening at port 3000......');});

Error: listen EADDRNOTAVAIL: address not available 192.168.0.101:3000 at Server.setupListenHandle [as _listen2] (node:net:1313:21) at listenInCluster (node:net:1378:12) at doListen (node:net:1516:7) at processTicksAndRejections (node:internal/process/task_queues:84:21)Emitted 'error' event on Server instance at: at emitErrorNT (node:net:1357:8) at processTicksAndRejections (node:internal/process/task_queues:83:21) { code: 'EADDRNOTAVAIL', errno: -99, syscall: 'listen', address: '192.168.0.101', port: 3000}

To resolve this issue, ensure that you have the right IP address (it maysometimes change), or you can bind to any or all IPs by using 0.0.0.0 as shownbelow:

var server = app.listen(3000, '0.0.0.0', function () { console.log('server listening at port 3000......');});

7. ECONNABORTED

The ECONNABORTED exception is thrown when an active network connection isaborted by the server before reading from the request body or writing to theresponse body has completed. The example below demonstrates how this problem canoccur in a Node.js program:

const express = require('express');const app = express();const path = require('path');app.get('/', function (req, res, next) { res.sendFile(path.join(__dirname, 'new.txt'), null, (err) => { console.log(err); }); res.end();});const server = app.listen(3000, () => { console.log('server listening at port 3001......');});

Error: Request aborted at onaborted (/home/ayo/dev/demo/node_modules/express/lib/response.js:1030:15) at Immediate._onImmediate (/home/ayo/dev/demo/node_modules/express/lib/response.js:1072:9) at processImmediate (node:internal/timers:466:21) { code: 'ECONNABORTED'}

The problem here is that res.end() was called prematurely beforeres.sendFile() has had a chance to complete due to the asynchronous nature ofthe method. The solution here is to move res.end() into sendFile()'scallback function:

app.get('/', function (req, res, next) { res.sendFile(path.join(__dirname, 'new.txt'), null, (err) => { console.log(err); res.end(); });});

8. EHOSTUNREACH

An EHOSTUNREACH exception indicates that a TCP connection failed because theunderlying protocol software found no route to the network or host. It can alsobe triggered when traffic is blocked by a firewall or in response to informationreceived by intermediate gateways or switching nodes. If you encounter thiserror, you may need to check your operating system's routing tables or firewallsetup to fix the problem.

9. EAI_AGAIN

Node.js throws an EAI_AGAIN error when a temporary failure in domain nameresolution occurs. A DNS lookup timeout that usually indicates a problem withyour network connection or your proxy settings. You can get this error whentrying to install an npm package:

npm ERR! code EAI_AGAINnpm ERR! syscall getaddrinfonpm ERR! errno EAI_AGAINnpm ERR! request to https://registry.npmjs.org/nestjs failed, reason: getaddrinfo EAI_AGAIN registry.npmjs.org

If you've determined that your internet connection is working correctly, thenyou should investigate your DNS resolver settings (/etc/resolv.conf) or your/etc/hosts file to ensure it is set up correctly.

10. ENOENT

This error is a straightforward one. It means "Error No Entity" and is raisedwhen a specified path (file or directory) does not exist in the filesystem. Itis most commonly encountered when performing an operation with the fs moduleor running a script that expects a specific directory structure.

fs.open('non-existent-file.txt', (err, fd) => { if (err) { console.log(err); }});

[Error: ENOENT: no such file or directory, open 'non-existent-file.txt'] { errno: -2, code: 'ENOENT', syscall: 'open', path: 'non-existent-file.txt'}

To fix this error, you either need to create the expected directory structure orchange the path so that the script looks in the correct directory.

11. EISDIR

If you encounter this error, the operation that raised it expected a fileargument but was provided with a directory.

// config is actually a directoryfs.readFile('config', (err, data) => { if (err) throw err; console.log(data);});

[Error: EISDIR: illegal operation on a directory, read] { errno: -21, code: 'EISDIR', syscall: 'read'}

Fixing this error involves correcting the provided path so that it leads to afile instead.

12. ENOTDIR

This error is the inverse of EISDIR. It means a file argument was suppliedwhere a directory was expected. To avoid this error, ensure that the providedpath leads to a directory and not a file.

fs.opendir('/etc/passwd', (err, _dir) => { if (err) throw err;});

[Error: ENOTDIR: not a directory, opendir '/etc/passwd'] { errno: -20, code: 'ENOTDIR', syscall: 'opendir', path: '/etc/passwd'}

13. EACCES

The EACCES error is often encountered when trying to access a file in a waythat is forbidden by its access permissions. You may also encounter this errorwhen you're trying to install a global NPM package (depending on how youinstalled Node.js and npm), or when you try to run a server on a port lowerthan 1024.

fs.readFile('/etc/sudoers', (err, data) => { if (err) throw err; console.log(data);});

[Error: EACCES: permission denied, open '/etc/sudoers'] { errno: -13, code: 'EACCES', syscall: 'open', path: '/etc/sudoers'}

Essentially, this error indicates that the user executing the script does nothave the required permission to access a resource. A quick fix is to prefix thescript execution command with sudo so that it is executed as root, but this isa bad ideafor security reasons.

The correct fix for this error is to give the user executing the script therequired permissions to access the resource through the chown command on Linuxin the case of a file or directory.

sudo chown -R $(whoami) /path/to/directory

If you encounter an EACCES error when trying to listen on a port lower than1024, you can use a higher port and set up port forwarding through iptables.The following command forwards HTTP traffic going to port 80 to port 8080(assuming your application is listening on port 8080):

sudo iptables -t nat -I PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

If you encounter EACCES errors when trying to install a global npm package,it usually means that you installed the Node.js and npm versions found in yoursystem's repositories. The recommended course of action is to uninstall thoseversions and reinstall them through a Node environment manager likeNVM or Volta.

14. EEXIST

The EEXIST error is another filesystem error that is encountered whenever afile or directory exists, but the attempted operation requires it not to exist.For example, you will see this error when you attempt to create a directory thatalready exists as shown below:

const fs = require('fs');fs.mkdirSync('temp', (err) => { if (err) throw err;});

Error: EEXIST: file already exists, mkdir 'temp' at Object.mkdirSync (node:fs:1349:3) at Object.<anonymous> (/home/ayo/dev/demo/main.js:3:4) at Module._compile (node:internal/modules/cjs/loader:1099:14) at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10) at Module.load (node:internal/modules/cjs/loader:975:32) at Function.Module._load (node:internal/modules/cjs/loader:822:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12) at node:internal/main/run_main_module:17:47 { errno: -17, syscall: 'mkdir', code: 'EEXIST', path: 'temp'}

The solution here is to check if the path exists through fs.existsSync()before attempting to create it:

const fs = require('fs');if (!fs.existsSync('temp')) { fs.mkdirSync('temp', (err) => { if (err) throw err; });}

15. EPERM

The EPERM error may be encountered in various scenarios, usually wheninstalling an npm package. It indicates that the operation being carried outcould not be completed due to permission issues. This error often indicates thata write was attempted to a file that is in a read-only state although you maysometimes encounter an EACCES error instead.

Here are some possible fixes you can try if you run into this problem:

1. Close all instances of your editor before rerunning the command (maybe somefiles were locked by the editor).
2. Clean the npm cache with npm cache clean --force.
3. Close or disable your Anti-virus software if have one.
4. If you have a development server running, stop it before executing theinstallation command once again.
5. Use the --force option as in npm install --force.
6. Remove your node_modules folder with rm -rf node_modules and install themonce again with npm install.

Conclusion

In this article, we covered 15 of the most common Node.js errors you are likelyto encounter when developing applications or utilizing Node.js-based tools, andwe discussed possible solutions to each one. This by no means an exhaustive listso ensure to check out theNode.js errors documentation or theerrno(3) man page for amore comprehensive listing.

Thanks for reading, and happy coding!

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