How to Fix Hydration Errors in Next.js
Hydration errors are one of the most common annoying issues you will face while working with Next.js, especially after upgrading to newer versions like Next.js 15 or 16. If your console shows messages like
don’t worry. This is a very common problem and easy to fix once you understand why it is happening.
In this guide, I will explain what causes hydration errors and I will show you simple real-world fix that actually works.
What is a Hydration Error in Next.js?
When you use Server-Side Rendering (SSR), Next.js first renders your page on the server and then sends HTML to the browser, React then "hydrates" the HTM basically reattaches event listeners and makes it interactive.
A hydration error happens when: The HTML on the server and client do not match.
This means:
Server rendered something
Client rendered something else
React gets confused → error appears
Why Hydration Errors Happen (Most Common Reasons) ?
Using Browser-Only APIs on Server Example -
Server doesn’t have these → mismatch happens.
2. Using Random Values on Server React renders different values on server vs client. Examples -
3. Conditional Rendering That Depends on Browser Example -
4. Using useEffect Data in Initial Render useEffect runs after hydration, so the initial HTML differs.
Fixes for Hydration Errors
1. Use "use client" for Browser-Specific Components
If your component depends on browser APIs or dynamic values, make it a client component.
2. Wrap Browser Code in useEffect()
Server does not run effects, so this prevents mismatch.
3. Use dynamic() with ssr: false
This is the cleanest fix when you don’t need SSR.
4. Avoid Random Values on Initial Render
Don't Do it
Do it
5. Fix Different Layout Rendering
If SSR and client show different markup, hydration will break.
Common example -
If isLoggedIn is based on localStorage, SSR will not find it.
Fix using -
Option A: Default to a loading state
Option B: Remove SSR (ssr:false)
Useful for dashboards and logged-in pages.
Some Quick Checklist to Avoid Hydration Errors
Issue | Fix |
Uses window/document | Move inside useEffect or use client |
Random values | Generate only on client |
Different markup server vs client | Use loading state |
Client-only library (charts, maps) | Use dynamic import + ssr:false |
Auth based on localStorage | Handle on client only |
Final Thoughts
Hydration errors feel irritating, but once you understand the cause, they are actually easy to fix. The simple rule is
Make sure the server and client render the same HTML on first render.
If they don’t → hydration breaks.
Next.js 16 improved hydration, but these issues are still happening when browser-only code leaks into server-rendered components.
Extra Tip: Quick Fix Using suppressHydrationWarning
If you are still confused about what is causing the hydration error, or you just want a quick temporary fix, Next.js provides a special attribute.
This tells React -
Ignore differences between server HTML and client HTML — don’t show hydration errors.
When should you use it?
When you're sure the mismatch is harmless
When some part of your UI renders differently on server vs client
When you're stuck and want to suppress the warning while debugging
Example (Next.js App Router)
In your /app/layout.tsx
Why this helps
React will no longer show hydration mismatch warnings for the <html> or its children.
Important note
This does not fix the root cause, it simply suppresses the warning. But if you don't know what’s happening and want a quick solution while you continue development
Just add it, it will silence the error immediately.
