"Next.js Hydration failed because the initial UI does not match what was rendered on the server"

Three likely causes and where to look.

Possible Issue #1 - Incorrect HTML Formatting

The error can occur due to incorrect HTML structure, such as placing a div element inside a p tag, using a ul list incorrectly, or nesting heading tags within p tags.

Basically, the mismatch between the client and server leads to hydration errors.

Possible Issue #2 - Browser Extensions Interference

Some browser extensions might modify the HTML content on the client side, leading to differences from the server-rendered content.

For example, an extension that inserts additional attributes or elements to all image tags can cause hydration issues.

Possible Issue #3 - Third-party Components Using Browser-specific Objects

If a third-party component relies on browser-specific objects like window, which are not available during server-side rendering, it can lead to hydration errors.

This is because the component might render differently (or not at all) on the server, compared to the client.