[backport v14]: fix(next/image): improve and simplify detect-content-type (#82118) #82179

ztanner · 2025-07-29T21:02:04Z

Backports:

fix(next/image): improve and simplify detect-content-type #82118

Add support for detecting more src image formats via magic number. The src image formats are handled as follows: - `image/jxl` - serve as is (since safari can render it) - `image/heic` - serve as is (since safari can render it) - `image/jp2` - serve as is (since safari can render it) - `application/pdf` - error (since no browser will render it) - `image/pic` - error (since no browser will render it) We also fallback to `sharp().metadata()` if we can't detect the magic number to ensure correctness.

vercel · 2025-07-29T21:02:11Z

Notifying the following users due to files changed in this PR based on this repo's notify modifiers:

@timneutkens, @ijjk, @shuding, @huozhi:

packages/next/src/server/serve-static.ts

packages/next/src/server/image-optimizer.ts

ijjk · 2025-07-29T22:16:18Z

Failing test suites

Commit: 3f00274

pnpm test-start test/e2e/app-dir/turbopack-reports/turbopack-reports.test.ts

turbopack-reports > should render page importing sqlite3

Expand output

● turbopack-reports › should render page importing sqlite3

next build failed with code/signal 1

  90 |           if (code || signal)
  91 |             reject(
> 92 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  93 |             )
  94 |           else resolve()
  95 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:92:15)

Read more about building and testing Next.js in contributing.md.

pnpm test-start test/e2e/prerender-native-module.test.ts

prerender native module > should render index correctly
prerender native module > should render /blog/first correctly
prerender native module > should render /blog/second correctly
prerender native module > should output traces

Expand output

● prerender native module › should render index correctly

next build failed with code/signal 1

  90 |           if (code || signal)
  91 |             reject(
> 92 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  93 |             )
  94 |           else resolve()
  95 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:92:15)

● prerender native module › should render /blog/first correctly

next build failed with code/signal 1

  90 |           if (code || signal)
  91 |             reject(
> 92 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  93 |             )
  94 |           else resolve()
  95 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:92:15)

● prerender native module › should render /blog/second correctly

next build failed with code/signal 1

  90 |           if (code || signal)
  91 |             reject(
> 92 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  93 |             )
  94 |           else resolve()
  95 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:92:15)

● prerender native module › should output traces

next build failed with code/signal 1

  90 |           if (code || signal)
  91 |             reject(
> 92 |               new Error(`next build failed with code/signal ${code || signal}`)
     |               ^
  93 |             )
  94 |           else resolve()
  95 |         })

  at ChildProcess.<anonymous> (lib/next-modes/next-start.ts:92:15)

● Test suite failed to run

TypeError: Cannot read properties of undefined (reading 'destroy')

  23 |     })
  24 |   })
> 25 |   afterAll(() => next.destroy())
     |                       ^
  26 |
  27 |   it('should render index correctly', async () => {
  28 |     const browser = await webdriver(next.url, '/')

  at Object.destroy (e2e/prerender-native-module.test.ts:25:23)

Read more about building and testing Next.js in contributing.md.

packages/next/src/server/image-optimizer.ts

ijjk · 2025-07-29T22:19:10Z

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
buildDuration	16.9s	15.3s	N/A
buildDurationCached	8.4s	7.1s	N/A
nodeModulesSize	201 MB	201 MB	⚠️ +13.2 kB
nextStartRea..uration (ms)	382ms	394ms	N/A

Client Bundles (main, webpack)

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
1a9f679d-HASH.js gzip	53.7 kB	53.7 kB	✓
5428.HASH.js gzip	181 B	180 B	N/A
6067-HASH.js gzip	5.14 kB	5.14 kB	✓
6428-HASH.js gzip	31.6 kB	31.6 kB	N/A
framework-HASH.js gzip	44.9 kB	44.9 kB	✓
main-app-HASH.js gzip	242 B	243 B	N/A
main-HASH.js gzip	34.2 kB	34.2 kB	N/A
webpack-HASH.js gzip	1.68 kB	1.68 kB	N/A
Overall change	104 kB	104 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Overall change	39.4 kB	39.4 kB	✓

Client Pages

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
_app-HASH.js gzip	196 B	196 B	✓
_error-HASH.js gzip	184 B	185 B	N/A
amp-HASH.js gzip	502 B	504 B	N/A
css-HASH.js gzip	321 B	324 B	N/A
dynamic-HASH.js gzip	1.82 kB	1.82 kB	N/A
edge-ssr-HASH.js gzip	258 B	257 B	N/A
head-HASH.js gzip	352 B	352 B	✓
hooks-HASH.js gzip	371 B	372 B	N/A
image-HASH.js gzip	4.32 kB	4.32 kB	N/A
index-HASH.js gzip	259 B	257 B	N/A
link-HASH.js gzip	2.67 kB	2.68 kB	N/A
routerDirect..HASH.js gzip	316 B	314 B	N/A
script-HASH.js gzip	385 B	386 B	N/A
withRouter-HASH.js gzip	311 B	310 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	654 B	654 B	✓

Client Build Manifests

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
_buildManifest.js gzip	484 B	481 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
index.html gzip	528 B	528 B	✓
link.html gzip	542 B	539 B	N/A
withRouter.html gzip	525 B	524 B	N/A
Overall change	528 B	528 B	✓

Edge SSR bundle Size

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
edge-ssr.js gzip	95.7 kB	95.7 kB	N/A
page.js gzip	3.06 kB	3.06 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
middleware-b..fest.js gzip	658 B	657 B	N/A
middleware-r..fest.js gzip	156 B	154 B	N/A
middleware.js gzip	25.6 kB	25.6 kB	✓
edge-runtime..pack.js gzip	839 B	839 B	✓
Overall change	26.4 kB	26.4 kB	✓

Next Runtimes

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
app-page-exp...dev.js gzip	172 kB	172 kB	✓
app-page-exp..prod.js gzip	98.4 kB	98.4 kB	✓
app-page-tur..prod.js gzip	100 kB	100 kB	✓
app-page-tur..prod.js gzip	94.4 kB	94.4 kB	✓
app-page.run...dev.js gzip	146 kB	146 kB	✓
app-page.run..prod.js gzip	92.9 kB	92.9 kB	✓
app-route-ex...dev.js gzip	22.6 kB	22.6 kB	✓
app-route-ex..prod.js gzip	16 kB	16 kB	✓
app-route-tu..prod.js gzip	16 kB	16 kB	✓
app-route-tu..prod.js gzip	15.7 kB	15.7 kB	✓
app-route.ru...dev.js gzip	22.2 kB	22.2 kB	✓
app-route.ru..prod.js gzip	15.7 kB	15.7 kB	✓
pages-api-tu..prod.js gzip	9.58 kB	9.58 kB	✓
pages-api.ru...dev.js gzip	9.85 kB	9.85 kB	✓
pages-api.ru..prod.js gzip	9.57 kB	9.57 kB	✓
pages-turbo...prod.js gzip	22.5 kB	22.5 kB	✓
pages.runtim...dev.js gzip	23.2 kB	23.2 kB	✓
pages.runtim..prod.js gzip	22.5 kB	22.5 kB	✓
server.runti..prod.js gzip	51.8 kB	51.8 kB	✓
Overall change	961 kB	961 kB	✓

build cache Overall increase ⚠️

	vercel/next.js 14-2-1	vercel/next.js ztanner/backport-82118	Change
0.pack gzip	1.65 MB	1.65 MB	N/A
index.pack gzip	114 kB	114 kB	⚠️ +242 B
Overall change	114 kB	114 kB	⚠️ +242 B

Diff details

Diff for middleware.js

Diff too large to display

Diff for edge-ssr.js

Diff too large to display

Commit: 3f00274

styfle · 2025-07-30T21:47:27Z

test/integration/image-optimizer/test/util.ts

@@ -1179,7 +1254,7 @@ export function runTests(ctx) {
    expect(res.status).toBe(200)
    expect(res.headers.get('Content-Type')).toBe('image/bmp')
    expect(res.headers.get('Cache-Control')).toBe(
-      `public, max-age=${isDev ? 0 : minimumCacheTTL}, must-revalidate`
+      `public, max-age=0, must-revalidate`


Hmm, I wouldn't expect this to change 🤔

Oh I see the same for ico so must be because of the bypass.

ijjk added created-by: Next.js team PRs by the Next.js team. tests type: next labels Jul 29, 2025

styfle reviewed Jul 29, 2025

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austinderek mentioned this pull request Jul 29, 2025

[backport v14]: fix(next/image): improve and simplify detect-content-type (#82118) austinderek/next.js#41

Closed

fix types & maxAge

1f65c9e

vercel bot reviewed Jul 29, 2025

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ztanner force-pushed the ztanner/backport-82118 branch 2 times, most recently from cce1a6e to d6057ed Compare July 30, 2025 00:08

revert unintended changes & fix failing tests

c253ab9

ztanner force-pushed the ztanner/backport-82118 branch from d6057ed to c253ab9 Compare July 30, 2025 00:12

ztanner added 3 commits July 29, 2025 17:15

remove unused const

539a961

revert unintended change

d0f4785

adjust test

3f00274

styfle reviewed Jul 30, 2025

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styfle approved these changes Jul 30, 2025

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ztanner merged commit 5dd68a5 into 14-2-1 Jul 30, 2025
88 of 101 checks passed

ztanner deleted the ztanner/backport-82118 branch July 30, 2025 22:02

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[backport v14]: fix(next/image): improve and simplify detect-content-type (#82118) #82179

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