How to Fix Next.js Hydration Mismatch Errors in App Router 30 Mar 2026 Post a Comment You are likely staring at a bright red error overlay or a cryptic console warning: "Hydration failed because the initial UI does not match wha… App Router errorsFrontend performanceNext.js hydration mismatchReact hydrationServer-side rendering SSRsuppressHydrationWarningwindow is not defined
