nextjs-404-troubleshooting

Next.js 15/16 breaking changes make route parameters Promise-based, causing 404 errors if not handled asynchronously. You must await these parameters in your dynamic route components to resolve the issue and ensure proper page generation.

To fix localStorage errors during Next.js Server-Side Rendering (SSR), add a window object check before accessing it. This guard prevents build failures and execution crashes because localStorage is only available in the browser environment.

Next.js 404 errors on subdomains and apex domains are caused by domain configuration mismatches. Unifying domain settings ensures consistency across apex and subdomain routing, allowing pages to generate and cache correctly.

Handle asynchronous parameters in Next.js by awaiting the Promise-based parameters in your page components. This resolves 404 errors from Next.js 15/16 breaking changes and ensures dynamic routes generate correctly during caching.

Server-Side Rendering in Next.js does not work directly with localStorage because it runs on the server. You must implement a window existence guard to prevent SSR build failures while retaining client-side storage functionality.