15 Common Error Codes in Node.js and How to Fix Them

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

Therefore, we've compiled this list of 15 common Node.js errors along with one or more strategies to follow to fix each one. While this is not a comprehensive list 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 feasible solutions to avoid future recurrence.

1. ECONNRESET

ECONNRESET is a common exception that occurs when the TCP connection to another server is closed abruptly, usually before a response is received. It can be emitted when you attempt a request through a TCP connection that has already been closed or when the connection is closed before a response is received (perhaps in case of a timeout). This exception will usually look 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 should catch it and decide how to handle it. For example, you can retry the request immediately, or queue it for later. You can also investigate your timeout settings if you'd like to wait longer for the request to be completed.

On the other hand, if it is caused by a client deliberately closing an unfulfilled request to your server, then you don't need to do anything except end the connection (res.end()), and stop any operations performed in generating a response. You can detect if a client socket was destroyed through the 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 be established to some host due to a DNS error. This usually occurs due to an incorrect host value, or when localhost is not mapped correctly to 127.0.0.1. 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, you can 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. You can also use a tool like DNS Checker to confirm that the 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 standard library, ensure that the host value in the options object contains only the domain name or IP address of the server. It shouldn't contain the protocol, port, or request path (use the protocol, port, and path properties for those values respectively).

// don't do this
const options = {
  host: 'http://example.com/path/to/resource',
};

// do this instead
const 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 and macOS, 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 service in 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 HTTP request is not closed properly after some time. You might encounter this error from time to time if you configured a timeout on your outgoing HTTP requests. The general solution to this issue is to catch the error and repeat the request, preferably using an exponential backoff strategy so that a waiting period is added between subsequent retries until the request eventually succeeds, or the maximum amount of retries is reached. If you encounter this error frequently, try to investigate your request timeout settings and choose a more appropriate value for the endpoint if possible.

4. ECONNREFUSED

The ECONNREFUSED error is produced when a request is made to an endpoint but a connection could not be established because the specified address wasn't reachable. This is usually caused by an inactive target service. For example, the error below resulted from attempting to connect to http://localhost:8000 when 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 and accepting connections at the specified endpoint.

5. ERRADDRINUSE

This error is commonly encountered when starting or restarting a web server. It indicates that the server is attempting to listen for connections at a port that is 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 listen on 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 ID of the application using it through the command below:

lsof -i tcp:3000

COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
node    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 closed freeing up the desired port for your intended use.

6. EADDRNOTAVAIL

This error is similar to EADDRINUSE because it results from trying to run a Node.js server at a specific port. It usually indicates a configuration issue with 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 may sometimes change), or you can bind to any or all IPs by using 0.0.0.0 as shown below:

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 is aborted by the server before reading from the request body or writing to the response body has completed. The example below demonstrates how this problem can occur 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 before res.sendFile() has had a chance to complete due to the asynchronous nature of the method. The solution here is to move res.end() into sendFile()'s callback 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 the underlying protocol software found no route to the network or host. It can also be triggered when traffic is blocked by a firewall or in response to information received by intermediate gateways or switching nodes. If you encounter this error, you may need to check your operating system's routing tables or firewall setup to fix the problem.

9. EAI_AGAIN

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

npm ERR! code EAI_AGAIN
npm ERR! syscall getaddrinfo
npm ERR! errno EAI_AGAIN
npm 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, then you 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 raised when a specified path (file or directory) does not exist in the filesystem. It is most commonly encountered when performing an operation with the fs module or 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 or change 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 file argument but was provided with a directory.

// config is actually a directory
fs.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 a file instead.

12. ENOTDIR

This error is the inverse of EISDIR. It means a file argument was supplied where a directory was expected. To avoid this error, ensure that the provided path 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 way that is forbidden by its access permissions. You may also encounter this error when you're trying to install a global NPM package (depending on how you installed Node.js and npm), or when you try to run a server on a port lower than 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 not have the required permission to access a resource. A quick fix is to prefix the script execution command with sudo so that it is executed as root, but this is a bad idea for security reasons.

The correct fix for this error is to give the user executing the script the required permissions to access the resource through the chown command on Linux in 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 than 1024, 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 your system's repositories. The recommended course of action is to uninstall those versions and reinstall them through a Node environment manager like NVM or Volta.

14. EEXIST

The EEXIST error is another filesystem error that is encountered whenever a file 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 that already 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 when installing an npm package. It indicates that the operation being carried out could not be completed due to permission issues. This error often indicates that a write was attempted to a file that is in a read-only state although you may sometimes 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 some files 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 the installation 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 them once again with npm install.

Conclusion

In this article, we covered 15 of the most common Node.js errors you are likely to encounter when developing applications or utilizing Node.js-based tools, and we discussed possible solutions to each one. This by no means an exhaustive list so ensure to check out the Node.js errors documentation or the errno(3) man page for a more comprehensive listing.

Thanks for reading, and happy coding!

Article by

Ayooluwa Isaiah

Ayo is a technical content manager at Better Stack. His passion is simplifying and communicating complex technical ideas effectively. His work was featured on several esteemed publications including LWN.net, Digital Ocean, and CSS-Tricks. When he's not writing or coding, he loves to travel, bike, and play tennis.

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