Error Tracking Nextjs

Next.js error tracking installation - Docs

1. 1

   Install the package

   Required

   Install the PostHog JavaScript library using your package manager:

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   npm

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   npm install posthog-js

   yarn

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   yarn add posthog-js

   pnpm

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   pnpm add posthog-js

2. 2

   Add environment variables

   Required

   Add your PostHog project token and host to your .env.local file and to your hosting provider (e.g. Vercel, Netlify). These values need to start with NEXT_PUBLIC_ to be accessible on the client-side.

   .env.local

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   NEXT_PUBLIC_POSTHOG_PROJECT_TOKEN=<ph_project_token>
   NEXT_PUBLIC_POSTHOG_HOST=https://us.i.posthog.com

3. 3

   Initialize PostHog

   Required

   Choose the integration method based on your Next.js version and router type.

   Next.js 15.3+

   If you're using Next.js 15.3+, you can use instrumentation-client.ts for a lightweight, fast integration:

   instrumentation-client.ts

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   import posthog from 'posthog-js'
   posthog.init(process.env.NEXT_PUBLIC_POSTHOG_PROJECT_TOKEN!, {
       api_host: process.env.NEXT_PUBLIC_POSTHOG_HOST,
       defaults: '2026-01-30'
   })

   App router

   For the App router, create a providers.tsx file in your app folder. The posthog-js library needs to be initialized on the client-side using the 'use client' directive:

   app/providers.tsx

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   'use client'
   import { usePathname, useSearchParams } from "next/navigation"
   import { useEffect } from "react"
   import posthog from 'posthog-js'
   import { PostHogProvider as PHProvider } from 'posthog-js/react'
   export function PostHogProvider({ children }: { children: React.ReactNode }) {
     useEffect(() => {
       posthog.init(process.env.NEXT_PUBLIC_POSTHOG_PROJECT_TOKEN as string, {
         api_host: process.env.NEXT_PUBLIC_POSTHOG_HOST,
         defaults: '2026-01-30'
       })
     }, [])
     return (
       <PHProvider client={posthog}>
         {children}
       </PHProvider>
     )
   }

   Then import the PostHogProvider component in your app/layout.tsx and wrap your app with it:

   app/layout.tsx

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   import './globals.css'
   import { PostHogProvider } from './providers'
   export default function RootLayout({ children }: { children: React.ReactNode }) {
     return (
       <html lang="en">
         <body>
           <PostHogProvider>
             {children}
           </PostHogProvider>
         </body>
       </html>
     )
   }

   Pages router

   For the Pages router, integrate PostHog at the root of your app in pages/_app.tsx:

   pages/_app.tsx

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   import { useEffect } from 'react'
   import { Router } from 'next/router'
   import posthog from 'posthog-js'
   import { PostHogProvider } from 'posthog-js/react'
   import type { AppProps } from 'next/app'
   export default function App({ Component, pageProps }: AppProps) {
     useEffect(() => {
       posthog.init(process.env.NEXT_PUBLIC_POSTHOG_PROJECT_TOKEN as string, {
         api_host: process.env.NEXT_PUBLIC_POSTHOG_HOST,
         defaults: '2026-01-30',
         loaded: (posthog) => {
           if (process.env.NODE_ENV === 'development') posthog.debug()
         }
       })
     }, [])
     return (
       <PostHogProvider client={posthog}>
         <Component {...pageProps} />
       </PostHogProvider>
     )
   }

   Defaults option

   The defaults option automatically configures PostHog with recommended settings for new projects. See SDK defaults for details.

4. 4

   Accessing PostHog on the client

   Recommended

   Next.js 15.3+

   Once initialized in instrumentation-client.ts, import posthog from posthog-js anywhere and call the methods you need:

   app/checkout/page.tsx

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   'use client'
   import posthog from 'posthog-js'
   export default function CheckoutPage() {
       function handlePurchase() {
           posthog.capture('purchase_completed', { amount: 99 })
       }
       return <button onClick={handlePurchase}>Complete purchase</button>
   }

   App/Pages router

   Use the usePostHog hook to access PostHog in client components:

   app/checkout/page.tsx

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   'use client'
   import { usePostHog } from 'posthog-js/react'
   export default function CheckoutPage() {
       const posthog = usePostHog()
       function handlePurchase() {
           posthog.capture('purchase_completed', { amount: 99 })
       }
       return <button onClick={handlePurchase}>Complete purchase</button>
   }

5. 5

   Capture client-side exceptions

   Required

   PostHog can automatically capture unhandled exceptions in your Next.js app using the JavaScript Web SDK.

   You can enable exception autocapture for the JavaScript Web SDK in the Error tracking section of your project settings.

   It is also possible to manually capture exceptions using the captureException method:

   JavaScript

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   posthog.captureException(error, additionalProperties)

   Manual capture is very useful if you already use error boundaries to handle errors in your app:

   App router

   Next.js uses error boundaries to handle uncaught exceptions by rendering a fallback UI instead of the crashing components. To set one up, create a error.tsx file in any of your route directories. This triggers when there is an error rendering your component and should look like this:

   error.tsx

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   "use client"
   import posthog from "posthog-js"
   import { useEffect } from "react"
   export default function Error({
     error,
     reset,
   }: {
     error: Error & { digest?: string }
     reset: () => void
   }) {
     useEffect(() => {
       posthog.captureException(error)
     }, [error])
     return (
       ...
     )
   }

   You can also create a Global Error component in your root layout to capture unhandled exceptions in your root layout.

   app/global-error.tsx

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   'use client'
   import posthog from "posthog-js"
   import NextError from "next/error"
   import { useEffect } from "react"
   export default function GlobalError({
     error,
     reset,
   }: {
     error: Error & { digest?: string }
     reset: () => void
   }) {
     useEffect(() => {
       posthog.captureException(error)
     }, [error])
     return (
       // global-error must include html and body tags
       <html>
         <body>
           {/* `NextError` is the default Next.js error page component */}
           <NextError statusCode={0} />
         </body>
       </html>
     )
   }

   Pages router

   For Pages Router, you can use React's Error Boundaries to catch JavaScript errors anywhere in the component tree. Create a custom error boundary component and report errors to PostHog in the componentDidCatch method:

   components/ErrorBoundary.tsx

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   componentDidCatch(error, errorInfo) {
     posthog.captureException(error)
   }

   Then wrap your app or specific components with the error boundary:

   pages/_app.tsx

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   import type { AppProps } from 'next/app'
   import ErrorBoundary from '../components/ErrorBoundary'
   export default function App({ Component, pageProps }: AppProps) {
     return (
       <ErrorBoundary>
         <Component {...pageProps} />
       </ErrorBoundary>
     )
   }

6. 6

   Installing PostHog SDK for server-side

   Required

   Next.js enables you to both server-side render pages and add server-side functionality. To integrate PostHog into your Next.js app on the server-side, you can use the Node SDK.

   First, install the posthog-node library:

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   npm

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   npm install posthog-node --save

   yarn

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   yarn add posthog-node

   pnpm

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   pnpm add posthog-node

   bun

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   bun add posthog-node

   For the backend, we can create a lib/posthog-server.js file. In it, initialize PostHog from posthog-node as a singleton with your project token and host from your project settings.

   This looks like this:

   lib/posthog-server.js

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   import { PostHog } from 'posthog-node'
   let posthogInstance = null
   export function getPostHogServer() {
     if (!posthogInstance) {
       posthogInstance = new PostHog(
         process.env.NEXT_PUBLIC_POSTHOG_PROJECT_TOKEN,
         {
           host: process.env.NEXT_PUBLIC_POSTHOG_HOST,
           flushAt: 1,
           flushInterval: 0,
         }
       )
     }
     return posthogInstance
   }

   You can now use the getPostHogServer function to capture exceptions in server-side code.

   JavaScript

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   const posthog = getPostHogServer()
   try {
       throw new Error("This is a test exception for error tracking")
   } catch (error) {
       posthog.captureException(error, {
           source: 'test',
           user_id: 'test-user-123',
       })
   }

7. Verify server-side exceptions

   Recommended

   You should also see events and exceptions in PostHog coming from your server-side code in the activity feed.

   Check for server events in PostHog

8. 7

   Capturing server-side exceptions

   Required

   To capture errors that occur in your server-side code, you can set up an instrumentation.ts file at the root of your project. This provides a onRequestError hook that you can use to capture errors.

   Importantly, you need to:

   1. Set up a posthog-node client in your server-side code. See our doc on setting up Next.js server-side analytics for more.

   2. Check the request is running in the nodejs runtime to ensure PostHog works. You can call posthog.debug() to get verbose logging.

   3. Get the distinct_id from the cookie to connect the error to a specific user.

   This looks like this:

   JavaScript

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   // instrumentation.js
   export function register() {
     // No-op for initialization
   }
   export const onRequestError = async (err, request, context) => {
     if (process.env.NEXT_RUNTIME === 'nodejs') {
       const { getPostHogServer } = require('./lib/posthog-server')
       const posthog = getPostHogServer()
       let distinctId = null
       if (request.headers.cookie) {
         // Normalize multiple cookie arrays to string
         const cookieString = Array.isArray(request.headers.cookie)
           ? request.headers.cookie.join('; ')
           : request.headers.cookie
         const postHogCookieMatch = cookieString.match(/ph_phc_.*?_posthog=([^;]+)/)
         if (postHogCookieMatch && postHogCookieMatch[1]) {
           try {
             const decodedCookie = decodeURIComponent(postHogCookieMatch[1])
             const postHogData = JSON.parse(decodedCookie)
             distinctId = postHogData.distinct_id
           } catch (e) {
             console.error('Error parsing PostHog cookie:', e)
           }
         }
       }
       await posthog.captureException(err, distinctId || undefined)
     }
   }

   You can find a full example of both this and client-side error tracking in our Next.js error monitoring tutorial.

9. Verify error tracking

   Recommended

   Confirm events are being sent to PostHog

   Before proceeding, let's make sure exception events are being captured and sent to PostHog. You should see events appear in the activity feed.

   Image: Activity feed with eventsImage: Activity feed with events

   Check for exceptions in PostHog

10. 8

    Upload source maps

    Required

    Great, you're capturing exceptions! If you serve minified bundles, the next step is to upload source maps to generate accurate stack traces.

    Let's continue to the next section.

    Upload source maps

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