Turbopack Worker Threads Rollback

Transcript

Good morning, this is Next.js Daily for Sunday, January 19th, 2026.

Tobias Koppers merged a significant revert today, rolling back Turbopack's worker threads bundling support. The feature, originally introduced in PR #87746, was causing build failures with the error "non-evaluatable module - Worker thread module must be evaluatable" when processing the thread-stream package. The revert removed 755 lines of code across 23 files, including all worker thread test cases and related Rust implementation code in the Turbopack bundler.

This rollback highlights ongoing challenges in Turbopack's module evaluation system, particularly with Node.js worker threads that require runtime code execution. The build error suggests Turbopack couldn't statically analyze certain worker thread modules, forcing the team to pull the feature until a more robust solution is developed.

The Next.js bot also pushed version 16.1.1-canary.33, updating package versions across the monorepo's 19 packages including core Next.js, ESLint configurations, and various utilities.

What's next: The team will likely need to redesign how Turbopack handles worker thread module bundling to support non-evaluatable code patterns. Developers using worker threads in Next.js applications should continue with the current stable implementation while this gets resolved.

That's your Next.js Daily update.