Cannot find module 'sanity-plugin-markdown' in Next.js 15

This is a classic TypeScript module resolution issue. Based on the official sanity-plugin-markdown GitHub repository, here's how to fix your error:

1. First, verify the installation

Make sure you've installed both required packages:

npm install sanity-plugin-markdown easymde@2

Note that easymde@2 is a required peer dependency that must be installed alongside the plugin.

2. Clear your cache and reinstall

Sometimes npm installations can be incomplete:

rm -rf node_modules package-lock.json
npm install

3. Restart your TypeScript server

If you're using VS Code:

• Press Cmd/Ctrl + Shift + P
• Type "TypeScript: Restart TS Server"
• Select it

This often resolves module resolution issues where TypeScript is caching old state.

4. Check your import statement

In your sanity.config.ts, make sure you're importing correctly:

import { markdownSchema } from 'sanity-plugin-markdown'

export default defineConfig({
  // ... other config
  plugins: [markdownSchema()],
})

5. Special case for Next.js (pages directory)

If you're using Next.js without the app directory (using the pages directory), you need to use a different import path because Next.js doesn't support CSS imports from node_modules:

import { markdownSchema } from 'sanity-plugin-markdown/next'

Then add this to the top of pages/_app.tsx:

import 'easymde/dist/easymde.min.css'

6. Verify your Node.js version

Since you're on Next.js 15, ensure you're running Node.js 20 or higher. You can check with:

node --version

7. Check your package.json

After installation, verify both packages appear in your package.json:

{
  "dependencies": {
    "sanity-plugin-markdown": "^6.0.0",
    "easymde": "^2.x.x"
  }
}

The most common causes are either an incomplete installation or the TypeScript server needing a restart. Try these steps in order and the error should resolve! If you're still having issues after trying all of these, double-check that your tsconfig.json has proper module resolution settings (though this is usually fine by default).