Heroku + Node: Cannot find module error

Question

My Node app is running fine locally, but has run into an error when deploying to Heroku. The app uses Sequelize in a /models folder, which contains index.js, Company.js and Users.js. Locally, I am able to import the models using the following code in /models/index.js:

// load models
var models = [
  'Company',
  'User'
];
models.forEach(function(model) {
  module.exports[model] = sequelize.import(__dirname + '/' + model);
});

This works fine, however, when I deploy to Heroku the app crashes with the following error:

Error: Cannot find module '/app/models/Company'
   at Function.Module._resolveFilename (module.js:338:15)
   at Function.Module._load (module.js:280:25)
   at Module.require (module.js:364:17)
   at require (module.js:380:17)
   at module.exports.Sequelize.import (/app/node_modules/sequelize/lib/sequelize.js:219:24)
   at module.exports.sequelize (/app/models/index.js:60:43)
   at Array.forEach (native)
   at Object.<anonymous> (/app/models/index.js:59:8)
   at Module._compile (module.js:456:26)
   at Object.Module._extensions..js (module.js:474:10)
Process exited with status 8

Initially I thought it was due to case sensitivity (local mac vs heroku linux), but I moved the file, made a git commit, and then moved back and committed again to ensure Company.js is capitalized in the git repository. This didn't solve the problem and I'm not sure what the issue could be.

Douglas Reid · Accepted Answer · 2021-01-14 17:45:22Z

137

The problem was due to case sensitivity and file naming. Mac OS X is case insensitive (but aware) whereas Heroku is based on Linux and is case sensitive. By running heroku run bash from my terminal, I was able to see how the /models folder appeared on Heroku's file system. The solution was to rename User.js and Company.js on my local system to new temporary files, commit the changes to git, then rename back to User.js and Company.js being mindful of the capitalized first letter and then committing the changes again via git. Previously I had tried to rename the files directly from user.js to User.js and company.js to Company.js but the git commit and case-sensitive file name changes did not reflect on Heroku.

edited Jan 14, 2021 at 17:45

Douglas Reid

3,8986 gold badges34 silver badges51 bronze badges

answered Oct 13, 2013 at 17:22

surfearth

3,1574 gold badges26 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Alejandro B. Over a year ago

I had this same problem and had been trying to figure it out for the longest time. Thank you and than @dankohn!

user966041 Over a year ago

YOU SIR ARE A FREAKING LEGEND. Had this wrong in the (auto generated) package.json file with „server.js“ instead of „Server.js“.

blubberbo Over a year ago

Bravo, this was just the ticket for me and my "Tools"/"tools" folder

Yudishtira Over a year ago

Wow - Thank you - had no idea what was going on - I had misnamed my models User file with lower case user.js on my initial push to heroku and even though I corrected it later on - the file stayed lower case

Om Fuke Over a year ago

this worked for me too I checked with Heroku run bash and my file was somehow capital and locally it was lowercase. thanks a lot

|

Dan Kohn · Accepted Answer · 2013-10-13 11:07:08Z

37

I can't see the exact fix, but you can figure it out yourself by running heroku run bash to log into a Heroku instance, then run node to enter a REPL, and try requiring the paths directly.

answered Oct 13, 2013 at 11:07

Dan Kohn

34.4k9 gold badges91 silver badges100 bronze badges

4 Comments

surfearth Over a year ago

Thanks for this helpful debugging tip which enabled me to fix the issue.

Yudishtira Over a year ago

I never knew you could look at your heroku file structure - this has been a life saver - Thanks!!!

user6221709 Over a year ago

still valid in 2021

Alex Antoine Over a year ago

What key words in REPL should I type?

Adrien Joly · Accepted Answer · 2017-12-17 15:24:34Z

7

For me, it was caused by a folder that I had accidentally included in .gitignore!

answered Dec 17, 2017 at 15:24

Adrien Joly

5,4444 gold badges31 silver badges44 bronze badges

Comments

timarcosdias · Accepted Answer · 2020-07-12 22:35:57Z

2

I've been through an error like this one and the cause was that I renamed a module module.js to Module.js and the Heroku cache was conflicting the names. You must disable module caching to avoid this kind of error:

$ heroku config:set NODE_MODULES_CACHE=false

Source: https://help.heroku.com/TO64O3OG/cannot-find-module-in-node-js-at-runtime

answered Jul 12, 2020 at 22:35

timarcosdias

3973 silver badges10 bronze badges

1 Comment

A-S Over a year ago

This didn't work for me. If you are working on MacOS and changed the case of a file's name, the only solution that worked for me is the first one, i.e. rename the file into a temporary name that differs not only by the letter's case, and then change it back... Thought it's worth mentioning to save others the time of testing this (BTW cache is a good thing, and I wouldn't waive it that easily)

lbragile · Accepted Answer · 2020-10-24 02:32:00Z

2

Not sure if this is the same issue as described here, but for me my require("dotenv").config() was not conditioned upon the environment that the code was running in, thus Heroku could not find it since it was installed as a devDependency.

Fix:

if (process.env.NODE_ENV !== "production") {
  require("dotenv").config();
}

answered Oct 24, 2020 at 2:32

lbragile

8,1703 gold badges39 silver badges73 bronze badges

Comments

Gustavo Máximo · Accepted Answer · 2020-10-05 04:38:46Z

0

One of my files had a lowercase name locally and it was required as a lowercase.

const Product = require('../models/product');

On the git repo it was capitalized.

'../models/Product'

The server was trying to require a file which did not exist. I had to use git mv to rename the file locally then reupload it to fix the issue.

answered Oct 5, 2020 at 4:38

Gustavo Máximo

6,7365 gold badges22 silver badges37 bronze badges

Comments

Iam_vgs · Accepted Answer · 2022-03-01 18:37:55Z

0

For me, I just deleted the older app from Heroku and created the new one via Heroku web, and then pushed the code to the newer one, and then it worked.

answered Mar 1, 2022 at 18:37

Iam_vgs

1

2 Comments

Community Over a year ago

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Francisco Puga Over a year ago

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

Mohit Saud · Accepted Answer · 2022-04-27 16:42:24Z

0

For me what I changed was:

File name was CheckPermissions and I changed it to checkPermissions and then hosted. Error occurred.
Then revert the changes and hosted. This time worked well.

answered Apr 27, 2022 at 16:42

Mohit Saud

1251 silver badge5 bronze badges

Comments

Ranjith Raj D · Accepted Answer · 2022-05-04 06:36:51Z

0

I faced the same issue and resolved using dockerizing my application.

Create dockerFile from node
set heroku stack as docker
Deploy

Ref : https://devcenter.heroku.com/categories/deploying-with-docker

answered May 4, 2022 at 6:36

Ranjith Raj D

3143 silver badges14 bronze badges

Collectives™ on Stack Overflow

Heroku + Node: Cannot find module error

9 Answers 9

7 Comments

4 Comments

Comments

1 Comment

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

9 Answers 9

7 Comments

4 Comments

Comments

1 Comment

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related