Next.js 16 deployment fails with "unexpected error" despite successful build

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1

Hi everyone,
I’m experiencing a persistent deployment failure on Vercel that I cannot resolve. My Next.js 16 project builds successfully - compilation passes, TypeScript checks pass, and static pages are generated - but the deployment fails every time with this error:
“An unexpected error occurred when running this build. This may be a transient issue, please try rebuilding your project.”
The build works perfectly on my local machine, so this appears to be an infrastructure issue on Vercel’s side.
I’ve tried multiple troubleshooting steps without success:

  • Downgraded from Next.js 16 to 15 - same error
  • Changed Node.js version from 22.x to 20.x - same error
  • Added VERCEL_PRERENDER_METADATA_BOUNDARY=1 environment variable - same error
  • Switched from Turbopack to Webpack - same error
  • Added output: ‘standalone’ to next.config.js - same error
  • Cleared build cache and redeployed multiple times - same error
    I’ve had multiple consecutive failed deployments with the same unexpected_error code. Any help would be greatly appreciated!

Current: My Next.js 16 project builds successfully (compilation passes, TypeScript checks pass, static pages generate) but the deployment fails with the error: “An unexpected error occurred when running this build. This may be a transient issue, please try rebuilding your project.”
Expected: The deployment should complete successfully after a successful build.
The build works perfectly on my local machine with npm run build. This issue occurs only on Vercel’s infrastructure.

next.config.js:
/** @type {import(‘next’).NextConfig} */
const nextConfig = {
images: {
unoptimized: true,
},
output: ‘standalone’,
};
module.exports = nextConfig;
Steps to reproduce:

  1. Push any commit to the main branch
  2. Vercel starts the build process
  3. Build compiles successfully (all routes listed, no errors)
  4. Deployment fails with “unexpected error”
    What I’ve tried:

  • Switched from Next.js 15 to 16 - same error

  • Changed Node.js from 22.x to 20.x - same error

  • Added VERCEL_PRERENDER_METADATA_BOUNDARY=1 env variable - same error

  • Switched from Turbopack to Webpack (–webpack flag) - same error

  • Added output: ‘standalone’ - same error

  • Cleared build cache - same error

  • Repository: github.com/DNO8/ScorchCoreWeb

- Branch: main

- Framework: Next.js 16.2.6

- Node.js: 20.x (also tried 22.x)

- Build region: Washington, D.C. (iad1)

- Plan: Hobby

- All routes are dynamic (server-rendered on demand)

- Local build works without issues

2

hello DANO, have you tried redeploying with clear cache enabled?

3

Hi! thanks for your answer, and yes i did, actually i tried remaking the poyect in vercel dashaboard also :frowning:

4

I finally got it deployed! I removed all the export const dynamic = "force-dynamic"; lines from the page.tsx files. I also tried deploying with just a layout (which removed all the page.tsx files) and only static routes, and it deployed correctly (no components other than the page.tsx file were removed). Then I gradually added my routes until the entire website was deployed. This doesn’t explain why the error occurred, but it shares my experience of how I got it working. I hope it helps if anyone else encounters the same problem :slight_smile: