CoffeePuma55644 As an additional test, I also removed Bun as the runtime for the build while keeping Bun enabled for the Serverless Functions. The build completed successfully, but every Server Function immediately returned an Internal Server Error at runtime. The only configuration that currently works reliably for me is to use Bun only as the package manager, while letting Next.js run with the default runtime for both the build and the Serverless Functions. Hopefully this additional information helps narrow down where the issue might be.
Louis Pretty much the same problem here. Since updating to 16.3, \bun run build\ (1.3.14) fails on my Railway deployment, although it works locally. Reverting back to 16.2.12 fixed the issue
Ryu Hi CoffeePuma55644, Since you reproduced it with a fresh Next.js 16.3 app, I’d treat this as a compatibility issue between Next.js 16.3 and the Bun runtime path, not just your application code. There are two separate things to separate here: Bun as package manager bun install Bun as the runtime used to execute the Next build bun run --bun next build For the Function runtime, Vercel’s Bun config currently uses: { "bunVersion": "1.x" } and Vercel manages the minor/patch version, so I wouldn’t assume you can force Functions specifically onto 1.3.14 from vercel.json. For the build/install side, Ve
