Log browser error and warnings in terminal by huozhi · Pull Request #88352 · vercel/next.js

huozhi · 2026-01-09T23:02:43Z

This PR enables browser log forwarding to terminal by default during development. Previously, developers had to explicitly opt-in to see browser console output in their terminal. Now, browser console.error and console.warn are automatically forwarded with the new default level of 'warn' (both warnings and errors)

Changes

Changed browserDebugInfoInTerminal default from false to 'warn'
Only console.error and console.warn are forwarded by default
Users can configure: 'error' (errors only), 'warn' (default), or 'verbose' (all logs)
Do not forward react replayed logs in browser

nextjs-bot · 2026-01-09T23:07:44Z

Tests Passed

packages/next/src/server/dev/browser-logs/source-map.ts

packages/next/src/server/dev/browser-logs/receive-logs.ts

nextjs-bot · 2026-01-09T23:20:38Z

Stats from current PR

🔴 1 regression, 2 improvements

Metric	Canary	PR	Change	Trend
node_modules Size	458 MB	458 MB	🔴 +144 kB (+0%)	▁▁▁▁▁
Turbo Build Time	4.395s	4.072s	🟢 323ms (-7%)	▁▃▁▁█
Turbo Build Time (cached)	4.390s	4.059s	🟢 331ms (-8%)	▁▃▁▁█

📊 All Metrics

📖 Metrics Glossary

Dev Server Metrics:

Listen = TCP port starts accepting connections
First Request = HTTP server returns successful response
Cold = Fresh build (no cache)
Warm = With cached build artifacts

Build Metrics:

Fresh = Clean build (no .next directory)
Cached = With existing .next directory

Change Thresholds:

Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
Size: Changes < 1KB AND < 1% are insignificant
All other changes are flagged to catch regressions

⚡ Dev Server

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	455ms	✓	▁▁▁▁█
Cold (Ready in log)	439ms	439ms	✓	▂▁▂▂█
Cold (First Request)	1.207s	1.128s	✓	▄▂▄▄█
Warm (Listen)	457ms	456ms	✓	▁▁▁▁█
Warm (Ready in log)	449ms	445ms	✓	▁▁▁▁█
Warm (First Request)	346ms	346ms	✓	▁▂▁▁█

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	456ms	456ms	✓	▁▁▁▁▁
Cold (Ready in log)	438ms	439ms	✓	▁▁▇▆▁
Cold (First Request)	1.754s	1.751s	✓	▁▁▅▅▂
Warm (Listen)	456ms	456ms	✓	▁▁▁▁▁
Warm (Ready in log)	438ms	438ms	✓	▁▁▅▅▁
Warm (First Request)	1.784s	1.774s	✓	▁▁▅▅▁

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.395s	4.072s	🟢 323ms (-7%)	▁▃▁▁█
Cached Build	4.390s	4.059s	🟢 331ms (-8%)	▁▃▁▁█

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	14.033s	14.029s	✓	▁▁▃▃▄
Cached Build	14.125s	14.159s	✓	▂▁▃▃▃
node_modules Size	458 MB	458 MB	🔴 +144 kB (+0%)	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **430 kB** → **431 kB** ⚠️ +680 B

82 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	790 B	792 B	✓
Total	790 B	792 B	⚠️ +2 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	449 B	450 B	✓
Total	449 B	450 B	⚠️ +1 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
2086.HASH.js gzip	169 B	N/A	-
2161-HASH.js gzip	5.41 kB	N/A	-
2747-HASH.js gzip	4.48 kB	N/A	-
4322-HASH.js gzip	52.3 kB	N/A	-
ec793fe8-HASH.js gzip	62.3 kB	N/A	-
framework-HASH.js gzip	59.8 kB	59.8 kB	✓
main-app-HASH.js gzip	251 B	254 B	🔴 +3 B (+1%)
main-HASH.js gzip	38.6 kB	39 kB	🔴 +423 B (+1%)
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
1596.HASH.js gzip	N/A	169 B	-
2658-HASH.js gzip	N/A	52.7 kB	-
6349-HASH.js gzip	N/A	4.46 kB	-
7019-HASH.js gzip	N/A	5.43 kB	-
b17a3386-HASH.js gzip	N/A	62.3 kB	-
Total	225 kB	226 kB	⚠️ +770 B

Polyfills

	Canary	PR	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Total	39.4 kB	39.4 kB	✓

Pages

	Canary	PR	Change
_app-HASH.js gzip	194 B	193 B	✓
_error-HASH.js gzip	182 B	182 B	✓
css-HASH.js gzip	336 B	335 B	✓
dynamic-HASH.js gzip	1.8 kB	1.8 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	352 B	349 B	✓
hooks-HASH.js gzip	385 B	384 B	✓
image-HASH.js gzip	580 B	580 B	✓
index-HASH.js gzip	259 B	258 B	✓
link-HASH.js gzip	2.5 kB	2.51 kB	✓
routerDirect..HASH.js gzip	319 B	317 B	✓
script-HASH.js gzip	385 B	387 B	✓
withRouter-HASH.js gzip	316 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.97 kB	7.96 kB	✅ -8 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	242 kB	242 kB	✓
Total	366 kB	367 kB	⚠️ +467 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	655 B	653 B	✓
middleware-r..fest.js gzip	155 B	156 B	✓
middleware.js gzip	32.9 kB	33.3 kB	🔴 +389 B (+1%)
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	34.6 kB	34.9 kB	⚠️ +388 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	738 B	738 B	✓
Total	738 B	738 B	✓

Build Cache

	Canary	PR	Change
0.pack gzip	3.66 MB	3.67 MB	🔴 +11.6 kB (+0%)
index.pack gzip	102 kB	100 kB	🟢 1.37 kB (-1%)
index.pack.old gzip	99 kB	98.8 kB	✓
Total	3.86 MB	3.87 MB	⚠️ +10 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	303 kB	304 kB	✓
app-page-exp..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	303 kB	304 kB	✓
app-page-tur..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	300 kB	300 kB	✓
app-page-tur..prod.js gzip	156 kB	156 kB	✓
app-page.run...dev.js gzip	300 kB	301 kB	✓
app-page.run..prod.js gzip	156 kB	156 kB	✓
app-route-ex...dev.js gzip	68.8 kB	68.8 kB	✓
app-route-ex..prod.js gzip	47.6 kB	47.6 kB	✓
app-route-tu...dev.js gzip	68.8 kB	68.8 kB	✓
app-route-tu..prod.js gzip	47.6 kB	47.6 kB	✓
app-route-tu...dev.js gzip	68.4 kB	68.4 kB	✓
app-route-tu..prod.js gzip	47.4 kB	47.4 kB	✓
app-route.ru...dev.js gzip	68.4 kB	68.4 kB	✓
app-route.ru..prod.js gzip	47.3 kB	47.3 kB	✓
dist_client_...dev.js gzip	324 B	324 B	✓
dist_client_...dev.js gzip	326 B	326 B	✓
dist_client_...dev.js gzip	318 B	318 B	✓
dist_client_...dev.js gzip	317 B	317 B	✓
pages-api-tu...dev.js gzip	41.2 kB	41.2 kB	✓
pages-api-tu..prod.js gzip	31.3 kB	31.3 kB	✓
pages-api.ru...dev.js gzip	41.1 kB	41.1 kB	✓
pages-api.ru..prod.js gzip	31.2 kB	31.2 kB	✓
pages-turbo....dev.js gzip	50.8 kB	50.8 kB	✓
pages-turbo...prod.js gzip	38.2 kB	38.2 kB	✓
pages.runtim...dev.js gzip	50.7 kB	50.7 kB	✓
pages.runtim..prod.js gzip	38.2 kB	38.2 kB	✓
server.runti..prod.js gzip	62.2 kB	62.2 kB	✓
Total	2.69 MB	2.69 MB	⚠️ +2.7 kB

📝 Changed Files (9 files)

Files with changes:

app-page-exp..ntime.dev.js
app-page-exp..time.prod.js
app-page-tur..ntime.dev.js
app-page-tur..time.prod.js
app-page-tur..ntime.dev.js
app-page-tur..time.prod.js
app-page.runtime.dev.js
app-page.runtime.prod.js
server.runtime.prod.js

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huozhi · 2026-01-09T23:51:07Z

Log browser error and warnings in terminal #88352 👈 (View in Graphite)
canary

This stack of pull requests is managed by Graphite. Learn more about stacking.

Turbopack and Webpack produce different column numbers in stack traces. - Turbopack: (6:13) - Webpack: (6:7) Added isTurbopack checks to differentiate these cases in: - error-recovery.test.ts: "can recover from a component error" test - ReactRefreshLogBox.test.ts: "conversion to class component (1)" test

The log file test should work with the new default browser log forwarding since it captures logs directly from the log file, not from CLI output.

React replays server logs in the browser for debugging. These logs were being forwarded to the terminal again, causing duplicates. - Add check for replayed logs in patchConsoleError using parseConsoleArgs - Skip forwardErrorLog when environmentName is set (indicates replayed log) - Update log-file test to normalize environment labels and filter browser forwarding noise

test/development/acceptance/ReactRefreshLogBox.test.ts

nextjs-bot added created-by: Next.js team PRs by the Next.js team. type: next labels Jan 9, 2026

vercel bot reviewed Jan 9, 2026

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packages/next/src/server/dev/browser-logs/source-map.ts Outdated Show resolved Hide resolved

packages/next/src/server/dev/browser-logs/receive-logs.ts Outdated Show resolved Hide resolved

packages/next/src/server/dev/browser-logs/receive-logs.ts Show resolved Hide resolved

huozhi force-pushed the browser-logs-errors-default branch from 08b1969 to af41f9d Compare January 9, 2026 23:50

nextjs-bot added the tests label Jan 9, 2026

huozhi force-pushed the browser-logs-errors-default branch from 7dd15e2 to 8523a49 Compare January 12, 2026 22:20

huozhi changed the title ~~wip~~ Log browser error and warnings in terminal Jan 12, 2026

huozhi added 13 commits January 13, 2026 18:44

browser default error and warn logging

1c3a281

update test

b64ac9a

update test

71110e0

update test

4c3d6ea

remove browserDebugInfoInTerminal override from log-file test

e43a345

The log file test should work with the new default browser log forwarding since it captures logs directly from the log file, not from CLI output.

update test snapshot

20df171

update forward log cond

1a22c07

fix test snapshot and add comment

2bed122

reduce log levels and align schema

bb911b3

add test for loglevel

d91cd4c

update test snapshot

cb17aa9

huozhi force-pushed the browser-logs-errors-default branch from 0a0f0c0 to cb17aa9 Compare January 13, 2026 17:44

huozhi marked this pull request as ready for review January 14, 2026 22:31

huozhi requested review from feedthejim, gaojude and timneutkens January 14, 2026 22:32

gaojude approved these changes Jan 14, 2026

View reviewed changes

timneutkens reviewed Jan 16, 2026

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test/development/acceptance/ReactRefreshLogBox.test.ts Outdated Show resolved Hide resolved

timneutkens approved these changes Jan 16, 2026

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huozhi added 3 commits January 16, 2026 14:06

rm extra owner stack in forward logs

264a143

revert test snapshot changes

5792f20

revert test snapshots

f20e1e1

huozhi merged commit 8cfdcac into canary Jan 16, 2026
290 of 292 checks passed

huozhi deleted the browser-logs-errors-default branch January 16, 2026 14:10

wyattjoh pushed a commit that referenced this pull request Jan 16, 2026

Log browser error and warnings in terminal (#88352)

591d0da

github-actions bot added the locked label Jan 31, 2026

github-actions bot locked as resolved and limited conversation to collaborators Jan 31, 2026

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Log browser error and warnings in terminal#88352

Log browser error and warnings in terminal#88352
huozhi merged 16 commits intocanaryfrom
browser-logs-errors-default

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🔴 1 regression, 2 improvements

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