Date or Time Mismatches

• Problem:

  new Date()

  or

  Date.now()

  causes mismatches between server and client render.
• Solution: Fetch date on the server and pass it as a prop.

Dynamic or Random Values

• Problem:

  Math.random()

  or dynamic values change between server and client render.
• Solution: Use

  useEffect

  for client-side dynamic values to avoid initial mismatch.

Client-Specific Logic (

window

• Problem: Using browser-specific code (

  window

  ,

  localStorage

  ) in SSR.
• Solution: Move logic inside

  useEffect

  to ensure it runs only on the client.

External Dynamic Data

• Problem: Data fetched on the client differs from server-side render.
• Solution: Fetch data in

  getServerSideProps

  or

  getStaticProps

  to ensure consistency.

Invalid HTML Nesting

• Problem: Improper HTML structure causes mismatches.
• Solution: Ensure valid and consistent HTML structure across server and client renders.

Browser Extensions

• Problem: Extensions alter HTML before React loads.
• Solution: Test in an incognito window or disable extensions.