February 21, 2025 / 454 /

Resolving the EPERM: Operation Not Permitted Error Caused by Concurrent Next.js Instances

I was working on a Next.js 15 project using pnpm, and when I tried to run the build command (pnpm build), I encountered the following error:

uncaughtException [Error: EPERM: operation not permitted, open 'C:\Users\USER\Desktop\My Projects\tooabstractive\.next\trace'] {
  errno: -4048,
  code: 'EPERM',
  syscall: 'open',
  path: 'C:\\Users\\USER\\Desktop\\My Projects\\tooabstractive\\.next\\trace'
}
 ELIFECYCLE  Command failed with exit code 1.

This error occurred because I was also running an instance of the app using pnpm dev (the development server) at the same time.

Once I closed the dev server, the issue was resolved, and the build process worked as expected.

What I Learned

1. Close the Development Server: I realized that running the development server (pnpm dev) while also attempting to build the project (pnpm build) caused a conflict, as both processes tried to access and modify the same files in the .next folder.

   • I stopped the development server by closing the terminal where pnpm dev was running or by pressing Ctrl + C in that terminal.

2. Run the Build Command: After closing the development server, I ran pnpm build again, and the build process completed successfully without the “EPERM: operation not permitted” error.

3. Avoid Running Multiple Instances Simultaneously: To prevent this issue from occurring in the future, I made sure to avoid running both the development server and the build process simultaneously.

   This way, only one instance has access to the .next folder at a time, preventing conflicts and permission issues.

By ensuring that only one process is accessing the .next folder at a time, I was able to successfully build my Next.js project without encountering the “EPERM: operation not permitted” error.