# Why am I receiving a missing module error when building my Node.js app on App Platform?

App Platform throws this error when a module required to run the app is missing from the `dependencies` section of the app’s `package.json` file. The error usually looks like this:

```shell
Error: Cannot find module 'exampleModule'
[2022-11-01 00:59:32] Require stack:
[2022-11-01 00:59:32] - /workspace/server.js
[2022-11-01 00:59:32] at Function.Module._resolveFilename (node:internal/modules/cjs/loader:985:15)
[2022-11-01 00:59:32] at Function.Module._load (node:internal/modules/cjs/loader:833:27)
[2022-11-01 00:59:32] at Module.require
:
:
(node:internal/modules/cjs/loader:868:12)
[2022-11-01 00:59:32] at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) {
[2022-11-01 00:59:32] code: 'MODULE_NOT_FOUND',
```

Sometimes developers mistakenly list the missing module in the `devDependencies` section of the `package.json` file instead of the `dependencies` section. The `devDependencies` section’s purpose is to list modules that are required to develop the app, such as linters and testing libraries. App Platform prunes the modules listed in the `devDependencies` section during the build process as they are not required to run the app. This process removes any modules that may have been erroneously listed in the `devDependencies` section.

To fix this problem, add the missing module to the `dependencies` section of your app’s `package.json` file. Alternatively, you can configure App Platform to skip the pruning process during deployment by setting one of the following [environment variables](https://docs.digitalocean.com/products/app-platform/how-to/use-environment-variables/index.html.md):

- For npm: `NPM_CONFIG_PRODUCTION=false`
- For Yarn: `YARN_PRODUCTION=false`

## Related Topics

[How do I fix the error "Record is managed by an App on this account, and cannot be deleted"?](https://docs.digitalocean.com/support/how-do-i-fix-the-error-record-is-managed-by-an-app-on-this-account-and-cannot-be-deleted/index.html.md): Use the app’s Settings tab to remove domains associated with App Platform apps.

[Why do I get the error “JavaScript heap out of memory” during deployment?](https://docs.digitalocean.com/support/why-do-i-get-the-error-javascript-heap-out-of-memory-during-deployment/index.html.md): Increase the heap memory by setting the environment variable NODE\_OPTIONS=–max-old-space-size=4096.

[How do I fix a "permission denied for schema public" error in my dev database?](https://docs.digitalocean.com/support/how-do-i-fix-a-permission-denied-for-schema-public-error-in-my-dev-database/index.html.md): Delete the existing dev database and create a new one. Then make sure that the app deployment completes successfully.