[GH-ISSUE #960] Apply sourcemaps by default during prerender in production build #205

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opened 2026-05-06 12:38:10 +02:00 by BreizhHardware · 0 comments

BreizhHardware commented

2026-05-06 12:38:10 +02:00

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Originally created by @github-actions[bot] on GitHub (Apr 29, 2026).
Original GitHub issue: https://github.com/cloudflare/vinext/issues/960

Next.js Change

Next.js now applies sourcemaps by default during prerender in next build. Previously this was gated behind an experimental config option (experimental.applySourceMaps or similar) which has now been removed.

Commit: 59c73ae
PR: #93280

What Changed

packages/next/src/server/config-shared.ts: option type updated.
packages/next/src/server/config.ts: 8 lines removed — likely the gating logic that previously toggled sourcemap application based on an experimental flag.
Removed from documentation (docs/01-app/02-guides/memory-usage.mdx, docs/01-app/03-api-reference/06-cli/next.mdx).
Removed from test fixtures' next.config.js files (root-suspense-dynamic, server-source-maps/edge), implying the flag is no longer needed to opt in.

The behavior is now: during next build prerender, server stack traces are rewritten through sourcemaps by default, producing more useful error output if a build-time render throws.

Impact on vinext

vinext runs prerender via the App Router RSC build pipeline, with its own production server (cloudflare/worker-entry.ts) and prod build flow (createBuilder + buildApp). Two concerns:

Default behavior parity: Build-time prerender errors in vinext should also surface with sourcemap-resolved stack traces by default, matching Next.js DX. If vinext currently has no sourcemap-application step during prerender, errors will point to bundled output rather than user source.
Config compatibility: Users migrating from Next.js may have removed (or be about to remove) experimental.applySourceMaps (or whichever exact key was removed) from their config. vinext should not warn or break on that key's absence, and should not require an opt-in to get the now-default behavior.

Suggested Action

Identify the exact config option name removed (the diff trims 8 lines from config.ts; check the PR for the key) and ensure vinext's config ingestion silently accepts/ignores both the present and absent forms.
Audit vinext's prerender pipeline (vp build / createBuilder flow + the App Router RSC build) for whether it applies sourcemaps to server-side stack traces. If not, add it as the default.
Add a test that triggers a build-time render error in a fixture and asserts the printed stack frames reference user source files, not bundled output.

Originally created by @github-actions[bot] on GitHub (Apr 29, 2026). Original GitHub issue: https://github.com/cloudflare/vinext/issues/960 ## Next.js Change Next.js now applies sourcemaps by default during prerender in `next build`. Previously this was gated behind an experimental config option (`experimental.applySourceMaps` or similar) which has now been removed. **Commit:** [`59c73ae`](https://github.com/vercel/next.js/commit/59c73aecc9b26fdde5d6cd525ccc433123e7f55a) **PR:** [#93280](https://github.com/vercel/next.js/pull/93280) ## What Changed - `packages/next/src/server/config-shared.ts`: option type updated. - `packages/next/src/server/config.ts`: 8 lines removed — likely the gating logic that previously toggled sourcemap application based on an experimental flag. - Removed from documentation (`docs/01-app/02-guides/memory-usage.mdx`, `docs/01-app/03-api-reference/06-cli/next.mdx`). - Removed from test fixtures' `next.config.js` files (`root-suspense-dynamic`, `server-source-maps/edge`), implying the flag is no longer needed to opt in. The behavior is now: during `next build` prerender, server stack traces are rewritten through sourcemaps by default, producing more useful error output if a build-time render throws. ## Impact on vinext vinext runs prerender via the App Router RSC build pipeline, with its own production server (`cloudflare/worker-entry.ts`) and prod build flow (`createBuilder` + `buildApp`). Two concerns: 1. **Default behavior parity**: Build-time prerender errors in vinext should also surface with sourcemap-resolved stack traces by default, matching Next.js DX. If vinext currently has no sourcemap-application step during prerender, errors will point to bundled output rather than user source. 2. **Config compatibility**: Users migrating from Next.js may have removed (or be about to remove) `experimental.applySourceMaps` (or whichever exact key was removed) from their config. vinext should not warn or break on that key's absence, and should not require an opt-in to get the now-default behavior. ## Suggested Action - Identify the exact config option name removed (the diff trims 8 lines from `config.ts`; check the PR for the key) and ensure vinext's config ingestion silently accepts/ignores both the present and absent forms. - Audit vinext's prerender pipeline (`vp build` / `createBuilder` flow + the App Router RSC build) for whether it applies sourcemaps to server-side stack traces. If not, add it as the default. - Add a test that triggers a build-time render error in a fixture and asserts the printed stack frames reference user source files, not bundled output.