If you're encountering an issue with Contentlayer when trying to upgrade to Next.js 14.2 or later from version 13, there's a simple fix that can resolve the problem.

The issue arises due to compatibility problems between next-contentlayer and Next.js 14.2+. Next.js 14.2 introduced some breaking changes that caused issues with the Contentlayer package.

Specifically, the next-contentlayer plugin, which integrates Contentlayer with Next.js projects, had a peer dependency on next versions ^12 || ^13.

However, with Next.js 14, the next package was updated to a newer version, causing a peer dependency mismatch when trying to install next-contentlayer.

This resulted in errors like npm ERR! ERESOLVE unable to resolve dependency tree when attempting to install next-contentlayer in a Next.js 14 project.

The root cause is that the next-contentlayer package was not immediately updated to support the latest next version 14, leading to the peer dependency conflict when upgrading to Next.js 14.2+.

In your project's package.json file, add the following code under the "devDependencies" section:

"overrides": {
  "next-contentlayer": {
    "next": "$next"
  }
}

This override tells Next.js to use the latest version of the next package for the next-contentlayer dependency, resolving the compatibility issue.

After adding this code, save the package.json file, and you should be able to upgrade to Next.js 14.2+ without any Contentlayer-related issues.

That's it! With this small change, you can smoothly upgrade your Next.js project to the latest version while ensuring that Contentlayer continues to work as expected.

Thank you Edgaras for the tip!