Here are quick fixes for the most common problems learners run into.
Code will not run
- Check the console for an error message and the line number.
- Make sure you did not delete starter code that the tests rely on.
- Verify that your function names and variable names match the instructions.
- If the message says "Babel/React is still loading," wait a moment and click Run again. Babel and the React UMDs load on demand for React/TypeScript lessons.
- Try pressing Run again. The execution environment occasionally times out.
The preview panel is blank
- Confirm the output tab is set to Preview instead of Console.
- Make sure the editor has an
htmlfile selected if the lesson expects rendered output. - For React/TypeScript previews, wait for Babel and React to finish loading, then click Run again.
- Check the browser console for JavaScript errors.
I cannot sign in
- Check your email and password.
- If you use GitHub OAuth, make sure you are signed in to the correct GitHub account.
- Try a different browser or clear cookies for nextdeveloper.com.
My progress disappeared
Progress is tied to your account. Make sure you are signed in with the same email. Lesson progress is not saved while you are signed out, so sign in before you start a lesson to keep your work synced across devices.
Still stuck?
Ask in the Community Forum or email hello@nextdeveloper.com.