May 28, 2024

Fixing a Next.js Hydration Error: My Debugging Story

  • JavaScript
  • Debugging
  • Error
  • NextJS
  • Tips & Tricks

It happens to all of us: we spend hours debugging trivial problems that should take mere minutes. Recently, I faced a similar situation while developing the blog for my personal website. I encountered a hydration error in Next.js, which turned out to be a real pain to debug. Here's a detailed account of the issue and how I resolved it.

The Grepper Extension

Before diving into the problem, let me introduce you to a tool that I frequently use: the Grepper extension. This extension is incredibly handy for getting quick answers from the coding community. You can learn more about it here.

The Hydration Error

While developing my blog, I encountered a hydration error in Next.js. You can learn more about this specific error here. Initially, I had no idea why this error was occurring, making the debugging process frustrating and time-consuming.

The Culprit: DOM Manipulation

After some investigation, I discovered that the hydration error was caused by the Grepper extension. I used code blocks in my rich text editor for the blog, and the Grepper extension manipulated the DOM on the webpage. This manipulation was the root cause of the hydration error.

The Solution

To prevent this from happening, I found a useful Super User article that provided a solution. Since I use Firefox, I followed these steps:

  1. Open about:config in Firefox.
  2. Search for extensions.webextensions.restrictedDomains.
  3. Add localhost to the list of restricted domains.

By doing this, I ensured that the Grepper extension (and any other extensions) would not interfere with my local development environment, preventing such hydration errors.


Debugging can sometimes lead us down a rabbit hole, but with the right tools and knowledge, we can find solutions to seemingly complex problems. I hope my experience with the error and its resolution helps you facing similar issues.

Cheers, David