cypress v15 support for node v20.x

[laurentS]

Description

In the migration notes for cypress v15, it is mentioned that it works on node v20+, but trying to run cypress v15.0.0 with older node v20 will fail at startup with variations of Your configFile is invalid and

import { defineConfig } from 'cypress';
^^^^^^

SyntaxError: Cannot use import statement outside a module

From node v20.6.0 onwards, the issue is fixed.

Obviously nobody would run a version of node that's over 2 years old, but filing this just in case someone else gets stuck trying to work this out 😅

With cypress v14.x, there was no issue.

[MikeMcC399]

@laurentS

Thanks for drawing attention to this issue!

Migrating to Cypress 15.0 > Node.js 20, 22 and 24+ support says only:

Cypress requires Node.js in order to install the Cypress binary and the supported versions are now Node.js 20, 22, 24 and above. Node.js versions 18 and 23 are no longer supported. See Node's release schedule.

It does not specify which minor / patch version of Node.js to use. In practice however, Node.js only supports the latest release of each release line, so for Node.js 20 that would be currently v20.19.4.

As you noted, there were changes made to the Node.js 20 release line.

Some relevant milestones are:

• initial Node.js 20.0.0 release on Apr 18,2023, through the
• Node.js 20.6.0 release on Sep 4, 2023, followed by the
• initial LTS Node.js 20.9.0 release on Oct 24, 2023, then
• Node.js 20.19.4 release on Jul 15, 2025, which is the latest Maintenance LTS release

During the Node.js 20 release line lifetime, Node.js has changed how it recognizes CommonJS / ECMAScript (ESM) type modules:

---

For Node.js v20.0.0 the esm > Enabling documentation section says:

---

In the current Node.js v20.19.4 release the esm > Enabling section says:

---

I was able to reproduce the issue you describe using cypress.config.js under Cypress 15.0.0 and Node.js v20.0.0 with no type field defined in package.json, however I had the same issue also with Cypress 14.5.4, so couldn't confirm that this is a regression.

When I renamed cypress.config.js to cypress.config.mjs, then I had no problem. For both Cypress 14.5.4 and 15.0.0 under Node.js v20.19.4, I was able to run Cypress successfully without changing the config file extension.

---

• Testing Cypress with Node.js v20.0.0 I did however notice another issue that I reported under Cypress shows multiple warnings "ExperimentalWarning: Custom ESM Loaders ..." for Node.js >=20.0.0 <=20.6.0 cypress#32395

Depending on the outcome of this issue, there may be documentation changes necessary.