With the release of Next.js 15 and React 19, developers have encountered challenges with package compatibility and dependency conflicts. These versions bring significant improvements, but the breaking changes can disrupt workflows, particularly during development and deployment. One common issue arises from incompatible packages that require manual intervention to install correctly.

In this blog, I’ll walk you through the problem and provide a solution to ensure smooth development and deployment.

The Problem: Package Compatibility

When upgrading to Next.js 15 and React 19, you might encounter errors like:

npm ERR! Could not resolve dependency:  
npm ERR! peer <package-name> is not compatible with react@^19.0.0  

These errors typically arise because some packages are not yet fully compatible with the latest versions of Next.js or React. The peerDependency conflicts force npm to halt the installation.

Real-world Scenario

Imagine you are trying to install a UI library or utility package, and npm refuses to proceed due to incompatible peer dependencies. This issue escalates when deploying applications on platforms like Vercel, where the build process halts due to these conflicts.

The Solution: Using --force

To bypass these dependency conflicts, npm provides the --force flag. This flag instructs npm to install the package regardless of peer dependency issues.

Step 1: Installing Packages Locally

During development, use the following command to resolve the dependency issues:
npm install <package-name> --force
This command forces npm to ignore dependency constraints and proceed with the installation.

Step 2: Handling Deployment on Platforms like Vercel

When deploying your Next.js 15 app, you might encounter similar issues during the build process. To ensure the deployment completes successfully, update your deployment configuration to include the --force flag in the install command.

For Vercel, you can achieve this by adding a custom install command in the project settings:

1. Go to your Vercel Dashboard.
2. Select your project.
3. Navigate to the Build & Development Settings.
4. Under the Install Command

npm install --force

Best Practices

While the --force flag resolves the issue, it’s essential to approach this workaround cautiously:

1. Check for Compatibility Updates: Regularly check if the conflicting packages have released updates compatible with Next.js 15 and React 19.
2. Monitor Application Behavior: Forced installations might lead to runtime issues. Test your application thoroughly after resolving dependencies with --force.
3. Submit Issues: If you encounter compatibility problems, report them to the package maintainers. This helps improve the ecosystem.

Conclusion

Next.js 15 and React 19 bring powerful features, but breaking changes can disrupt workflows. Using npm install --force is a temporary workaround to handle dependency conflicts during development and deployment. While this method is effective, it’s crucial to stay updated with package compatibility and test your application rigorously.

Happy coding with Next.js 15 and React 19! 🚀