[ES6] [React] [NextJS14] [EJ2 31.1.20] `registerLicense` causes `Reference error: window not defined` during SSR

[sbougerel]

Issue

import { registerLicense } from '@syncfusion/ej2-base';
// ...
registerLicense(syncFusionLicenseKey);

Leads to errors during Server-Side Rendering in NextJS14:

 ⨯ ReferenceError: window is not defined

How to reproduce

Prepare a standard NextJS14 project. Copy the code above in one of the routable page.tsx path. Visit that path.

Given the issue, I don't think it's isolated to NextJS14, I think any component that uses SSR would have the same issue.

Current workaround

Load the component dynamically and disable SSR:

const MyEj2Component = dynamic(() => import('./my-ej2-component'), {
  ssr: false,
});

When did this issue occur?

Issue started to occur when we switched to:

    "@syncfusion/ej2-react-navigations": "^31.1.20",
    "@syncfusion/ej2-react-schedule": "^31.1.21",

Previously using:

    "@syncfusion/ej2-react-navigations": "^30.2.7",
    "@syncfusion/ej2-react-schedule": "^30.2.7",

Other solutions explored

• Upgrading to the latest version did not work
• Calling registerLicense during useLayoutEffect did not work

Additional information

package.json engines, dependencies:

  "engines": {
    "npm": ">=10.0.0",
    "node": "^22.18.0"
  },
  "dependencies": {
    "next": "^14.2.32",
    "react": "^18.3.1",
  }

[Deepika5698]

Hi @sbougerel ,

Thank you for reaching out.

We have thoroughly validated the issue from our end and successfully reproduced the reported issue. After careful analysis, we have identified it as a bug and have promptly logged a defect report on our end and scheduled to be resolved in our upcoming patch release, scheduled on December 9, 2025.

Instead of registering license through registerLicense method, you can also register the license through the npx command as an alternative approach. You can register the Syncfusion license in text file and activate through npx command. Refer to the documentation for more reference: https://ej2.syncfusion.com/react/documentation/licensing/license-key-registration#register-syncfusion-license-key-using-the-npx-command

Regards,
Deepika

[Deepika5698]

Hi @sbougerel,

Greetings from Syncfusion!

We’re glad to inform you that the reported issue with the registerLicense method during SSR has been resolved. The fix is now available in our weekly patch release version 31.2.18.
You can upgrade to the latest package using the link below:
https://www.npmjs.com/package/@syncfusion/ej2-base/v/31.2.18

Please let us know if you encounter any further issues or need assistance. We’re happy to help!

Regards,
Deepika