Type error in Sanity config file - how to troubleshoot?

Type errors in your sanity.config.ts file can be tricky to diagnose, but there are several common culprits you can check. Let me walk you through the most frequent causes and how to troubleshoot them.

First, check your Node.js and package versions

If you're using Sanity Studio v4, make sure you have:

• Node.js 20+ (Studio v4 requires this)
• Latest versions of sanity and related packages

Try running npm install sanity@latest or yarn upgrade sanity to ensure you have compatible versions.

Common type error causes

1. Missing or incorrect imports

Your config file needs proper imports at the top. A basic v3/v4 config should look like:

import {defineConfig} from 'sanity'
import {structureTool} from 'sanity/structure' // Note: v4 uses structureTool, v3 uses deskTool
import {visionTool} from '@sanity/vision'

If you're getting errors on defineConfig, make sure it's imported from 'sanity' not from another package.

2. Schema not properly registered

One of the most common issues is schemas not being added to your config. Make sure your schema types are imported and added to the schema.types array:

import {defineConfig} from 'sanity'
import {myDocumentType} from './schemas/myDocumentType'

export default defineConfig({
  // ... other config
  schema: {
    types: [myDocumentType], // Make sure all your types are here
  },
})

3. Using defineField or defineType incorrectly

If you're using TypeScript helpers like defineField, defineType, or defineArrayMember in your schema files, ensure they're imported correctly:

import {defineField, defineType} from 'sanity'

These helpers provide type safety but can throw errors if not used properly with the expected property types. According to the defineField documentation, these functions help catch type errors at compile time.

4. Plugin configuration issues

If you recently added a plugin, check its TypeScript types are installed. Some plugins require separate type packages or have specific configuration requirements.

Debugging steps

1. Check your IDE/editor: Hover over the red squiggly line to see the specific TypeScript error message
2. Run the TypeScript compiler: Try npx tsc --noEmit in your terminal to see detailed type errors
3. Check your tsconfig.json: Ensure it includes your Sanity files and has appropriate compiler options
4. Clear node_modules: Sometimes rm -rf node_modules package-lock.json && npm install resolves phantom type errors
5. Check for multiple TypeScript versions: Run npm ls typescript to ensure you don't have conflicting versions

Still stuck?

If you can share the specific error message (hover over the error in your IDE or run npx tsc), that would help narrow down the exact issue. Common error messages include:

• "Type X is not assignable to type Y"
• "Module has no exported member"
• "Cannot find name 'defineConfig'"

Each of these points to different solutions. The TypeScript error message is your best friend for debugging these issues! Feel free to share the specific error and we can help you further.