How to Fix Type Error in Next.js 15: Does Not Satisfy PageProps

If you’re building a Next.js 15 application with TypeScript, you might have stumbled upon the error: “Type ‘{ params: { id: string; }; }’ does not satisfy the constraint ‘PageProps’”. This TypeScript error can be confusing, especially when working with dynamic routes or App Router in Next.js. Don’t worry—this guide will break down what this error means, why it occurs, and how to fix it in simple, beginner-friendly language.

What Is the “Type { params: { id: string; }; } Does Not Satisfy PageProps” Error?

This error occurs in Next.js 15 when TypeScript detects a mismatch between the expected props for a page component and the props you’re providing. Specifically, it’s related to the PageProps type (or similar constraints) used in the App Router for dynamic routes. The error message typically looks like this:

Type '{ params: { id: string; }; }' does not satisfy the constraint 'PageProps'.
  Types of property 'params' are incompatible.
    Type '{ id: string; }' is not assignable to type 'Record<string, string | string[]>'.
      Property 'id' is incompatible with index signature.
        Type 'string' is not assignable to type 'string | string[]'.

What does this mean?

• PageProps: In Next.js 15’s App Router, PageProps is a TypeScript interface that defines the props a page component receives, including params (for dynamic route parameters) and searchParams (for query strings).
• The Issue: The error indicates that the params object (e.g., { id: string }) doesn’t match the expected type for PageProps, which requires params to be a Record<string, string | string[]>. This means params values can be either a single string or an array of strings (to support catch-all or optional catch-all routes).
• Common Context: This error often appears in dynamic routes (e.g., /pages/[id].tsx) or when defining props for a page component incorrectly.

Question: Can you think of a situation in your Next.js project where you defined a dynamic route? For example, did you create a file like [id].tsx or use params in your component?

Why Does This Error Happen in Next.js 15?

To fix this error, let’s explore its common causes:

• Incorrect Type Definition: You defined the params prop as { id: string }, but Next.js expects params to support string | string[] for dynamic routes (e.g., catch-all routes like [...slug]).
• Dynamic Routes Misconfiguration: Using dynamic routes (e.g., [id].tsx) without properly typing the page component’s props.
• Outdated TypeScript Types: Using types from an older Next.js version that don’t align with Next.js 15’s App Router.
• Missing or Incorrect Props: The page component doesn’t explicitly define PageProps or its equivalent, causing TypeScript to infer an incompatible type.
• Middleware or Route Handlers: Incorrectly handling params in middleware or API routes, leading to type mismatches.
• Third-Party Libraries: Libraries or templates (e.g., Next.js starters) may use outdated TypeScript configurations.

Question: Which of these causes might apply to your project? For instance, are you using dynamic routes, and how are you typing your page components?

Real-World Scenarios

Here are common scenarios where this error appears:

• Dynamic Route Page: A file like app/[id]/page.tsx with a component expecting params: { id: string } but not accounting for string | string[].
• Catch-All Routes: Using [...slug] or [[...slug]] routes, which require params values to be arrays.
• Custom Props: Combining params with custom props in a page component without proper typing.
• TypeScript Strict Mode: Enabling strict mode in tsconfig.json, which enforces stricter type checks.

How to Debug the Next.js Type Error PageProps

Debugging this error involves identifying where the type mismatch occurs and ensuring your code aligns with Next.js 15’s expectations. Let’s explore the steps.

Step 1: Check Your Route Structure

Confirm you’re using the App Router (Next.js 13+) and that your dynamic route is set up correctly:

• File Structure: For a dynamic route like /post/123, your file should be app/post/[id]/page.tsx.
• Catch-All Routes: For routes like /post/123/456, use app/post/[...slug]/page.tsx.

Question: What’s the difference between a dynamic route like [id] and a catch-all route like [...slug]? How might this affect the params type?

Step 2: Inspect Your Page Component

Look at the page component (e.g., app/[id]/page.tsx). A typical component might look like this:

export default function Page({ params }: { params: { id: string } }) {
  return <div>Post ID: {params.id}</div>;
}

The error occurs because { id: string } doesn’t satisfy Record<string, string | string[]>. Next.js expects params to handle both single strings (for [id]) and arrays (for [...slug]).

Step 3: Use TypeScript Debugging Tools

• VS Code: Hover over the params prop to see TypeScript’s inferred type and the expected PageProps type.
• TS Error Output: Check the full error in your terminal or editor to identify the exact file and line.
• Next.js Types: Import types from next to ensure you’re using the latest definitions:import { NextPage } from 'next';

Question: How can tools like VS Code’s TypeScript support help you spot type errors early?

How to Fix the Type Error in Next.js 15

Let’s explore practical solutions to resolve this Next.js Type Error PageProps, starting with the most common fixes.

Fix 1: Use Correct PageProps Type

Next.js provides built-in types for App Router pages. Update your page component to use NextPage or explicit PageProps:

import { NextPage } from 'next';

interface PageProps {
  params: { id: string };
  searchParams: { [key: string]: string | string[] | undefined };
}

const Page: NextPage<PageProps> = ({ params }) => {
  return <div>Post ID: {params.id}</div>;
};

export default Page;

This ensures params and searchParams match Next.js 15’s expectations.

Question: Why does Next.js require searchParams in the PageProps interface, even if you’re not using query strings?

Fix 2: Handle Catch-All Routes

If you’re using catch-all routes ([...slug] or [[...slug]]), params.slug must be typed as string[]:

import { NextPage } from 'next';

interface PageProps {
  params: { slug: string[] };
  searchParams: { [key: string]: string | string[] | undefined };
}

const Page: NextPage<PageProps> = ({ params }) => {
  return <div>Slug: {params.slug.join('/')}</div>;
};

export default Page;

For optional catch-all routes ([[...slug]]), params.slug can be string[] | undefined.

Question: How does a catch-all route differ from a single dynamic route in terms of the params object?

Fix 3: Use DynamicParams Type for Flexibility

If your route might handle both single parameters and arrays, use a more flexible type:

import { NextPage } from 'next';

interface PageProps {
  params: Record<string, string | string[]>;
  searchParams: { [key: string]: string | string[] | undefined };
}

const Page: NextPage<PageProps> = ({ params }) => {
  const id = Array.isArray(params.id) ? params.id[0] : params.id;
  return <div>Post ID: {id}</div>;
};

export default Page;

This satisfies the Record<string, string | string[]> constraint.

Fix 4: Update Next.js and TypeScript

Ensure you’re using the latest Next.js and TypeScript versions:

1. Check Versions:npm list next typescript
2. Update:npm install next@latest typescript@latest @types/node@latest
3. Check tsconfig.json:
   Ensure it includes:{ "compilerOptions": { "target": "es5", "lib": ["dom", "dom.iterable", "esnext"], "module": "esnext", "moduleResolution": "node", "jsx": "preserve", "strict": true } }

Question: Why might outdated dependencies cause TypeScript errors in Next.js?

Fix 5: Handle Middleware or Route Handlers

If the error occurs in middleware or API routes, ensure you’re typing the params correctly:

import { NextRequest, NextResponse } from 'next/server';

export async function GET(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  return NextResponse.json({ id: params.id });
}

For middleware:

import { NextRequest, NextResponse } from 'next/server';

export function middleware(request: NextRequest) {
  const params = request.nextUrl.pathname.split('/').filter(Boolean);
  return NextResponse.next();
}

Question: How do middleware and route handlers differ from page components in handling params?

Best Practices for TypeScript in Next.js 15

To prevent this and other TypeScript errors:

• Use Next.js Types: Always import types like NextPage, GetServerSideProps, or GetStaticProps from next.
• Enable Strict Mode: Set "strict": true in tsconfig.json to catch errors early.
• Type Dynamic Routes Correctly: Use Record<string, string | string[]> for params in dynamic routes.
• Keep Dependencies Updated: Regularly update Next.js, TypeScript, and related packages.
• Use ESLint: Enable the @typescript-eslint plugin to catch type issues.
• Test Routes: Test dynamic routes in development to ensure props are handled correctly.

Question: Which of these practices could you adopt to improve your Next.js TypeScript workflow?

Tools for TypeScript and Next.js

Tool	Purpose	Cost
ESLint	Catch TypeScript errors	Free
VS Code	TypeScript IntelliSense	Free
TypeScript Playground	Test TypeScript snippets	Free
Vercel	Deploy and debug Next.js apps	Free/Paid

Common Scenarios and Fixes

Scenario	Fix
Dynamic route [id]	Use params: { id: string } with PageProps
Catch-all route [...slug]	Type params: { slug: string[] }
Outdated Next.js version	Update to Next.js 15
Incorrect middleware typing	Use NextRequest and correct params

FAQs About Next.js Type Error PageProps

Why does this error only appear with TypeScript?

TypeScript enforces strict type checking, catching mismatches that JavaScript would ignore.

Can I ignore this error by disabling strict mode?

Disabling strict mode may hide the error but can lead to runtime issues. It’s better to fix the types.

Does this error affect Next.js 14 or earlier?

Yes, but Next.js 15’s updated App Router types are stricter, making this error more common.

How do I know if my route is dynamic or catch-all?

Check your file structure: [id] is dynamic, [...slug] is catch-all, and [[...slug]] is optional catch-all.

Conclusion: Master TypeScript in Next.js 15

The Next.js Type Error “Type { params: { id: string; }; } does not satisfy PageProps” is a common TypeScript hurdle, but it’s fixable with proper typing and an understanding of Next.js 15’s App Router. By using NextPage, typing params correctly, and keeping your dependencies updated, you can resolve this error and build robust applications in 2025.

Ready to fix this error? Update your page component with the correct PageProps type and test your dynamic routes. Have you encountered this error before? Share your experience in the comments below!

Resource: For more TypeScript and Next.js tips, visit the Next.js Documentation.