How do I resolve the 'docusign-esign' module not found error in my n8n workflow on Heroku?

Below is some guidance on how to resolve the missing module error for "docusign-esign" in your Code node.

Why the Error Occurs

n8n’s Code node expects all external modules you reference using require to be installed in the same environment as n8n. When the node execution sandbox (powered by vm2) can’t find the module, it will throw an error such as:

JSONCopied
{
  "errorMessage": "Cannot find module 'docusign-esign' [line 4]",
  "errorDescription": "VMError",
  "errorDetails": {},
  "n8nDetails": {}
}

Steps to Troubleshoot and Fix

1. Install the Module in Your Environment
   On platforms where you self-host n8n (including Heroku deployments on a dyno), you must install the module into your n8n environment. Make sure that the docusign-esign package is added to your application’s dependencies. For example, if you are using npm, add it to your package.json and run:

   BASHCopied
   npm install docusign-esign

2. Ensure the Module is Available at Runtime
   With environments like Heroku it’s important that the installation is properly persisted during deployment. Confirm that during the build process the module gets installed. If you’re using a custom build or deployment script, double-check that the module is included.

3. Update Environment Variables (if necessary)
   If your setup requires it, set the environment variables that allow the Code node’s sandbox to access external modules. In particular, verify the settings for:

   • NODE_FUNCTION_ALLOW_BUILTIN
   • NODE_FUNCTION_ALLOW_EXTERNAL

   These can sometimes be necessary if you require modules not available by default.

4. Verify Your Deployment Method
   Since you mentioned you’re running on a Heroku dyno, remember that cloud environments (even self-hosted ones like on Heroku) might recreate your dyno on each deployment or restart. This means the module must be declared as a dependency and installed every time.

   If you’re using a custom Dockerfile on Heroku, consider extending the image to install the extra module:

   DOCKERFILECopied
   RUN cd /usr/local/lib/node_modules/n8n && npm install docusign-esign

   But if you’re deploying directly with Heroku’s build process, adding the module to your package.json should suffice.

Summary

In your case, the error indicates that the runtime cannot find the docusign-esign module. To resolve it, ensure that:

• The module is part of your package dependencies.
• It is installed during your Heroku build.
• Your environment variables allow external modules if required.

Following these steps should help you clear the module error and have your Code node execute as expected.