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fix: fall back to page actions when a sibling endpoint has no POST handler - #16349

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Bishwas-py:fallback-to-actions-on-post
Jul 20, 2026
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fix: fall back to page actions when a sibling endpoint has no POST handler#16349
Rich-Harris merged 4 commits into
sveltejs:version-3from
Bishwas-py:fallback-to-actions-on-post

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@Bishwas-py

@Bishwas-py Bishwas-py commented Jul 14, 2026

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closes #10863

is_endpoint_request() routes POST to a sibling +server.js whenever the request isn't a native form submission (no x-sveltekit-action header) and the Accept header doesn't clearly prefer text/html. If that endpoint has no POST handler, render_endpoint returns a bare 405 instead of ever trying the page's actions, even when the page has a matching action that could serve the request.

This adds one check after the endpoint is resolved: if it's a POST and the endpoint has neither POST nor fallback, treat it as unusable and fall through to the page instead. This mirrors the endpoint_can_handle pattern already used for GET/HEAD in version-3 (#16125), extended here to POST for main.

New fixture at endpoint-output/actions-with-endpoint: a page with actions next to a +server.js that only exports GET.

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Install the latest version of @sveltejs/kit from 70ba949:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/70ba94900edcbe8336a8c4bcdaa2fecc193725fd

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16349

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This PR is from a fork. A maintainer must approve approve each commit before it can be built and installed.

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🦋 Changeset detected

Latest commit: 70ba949

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package
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@teemingc

teemingc commented Jul 18, 2026

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Hi there. We're currently developing against the version-3 branch. Do you mind rebasing your PR to that branch instead?

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teemingc previously requested changes Jul 18, 2026
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Needs to target the version-3 branch

@Bishwas-py
fix: fall back to page actions when a sibling endpoint has no POST ha…
581b953 
…ndler

Extends the endpoint_can_handle check to POST, alongside the
existing GET/HEAD handling. If a POST request would go to a
sibling +server.js with no POST handler and no fallback, fall
through to the page's actions instead of returning a bare 405.
@Bishwas-py
Bishwas-py force-pushed the fallback-to-actions-on-post branch from ffc839b to 581b953 Compare July 18, 2026 14:45
@Bishwas-py
Bishwas-py changed the base branch from main to version-3 July 18, 2026 14:45
@Bishwas-py

Bishwas-py commented Jul 18, 2026

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rebased onto version-3 in 581b953. also extended the same endpoint_can_handle check that already exists there for GET/HEAD (#16125) to cover POST, rather than reintroducing a separate check.

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Bishwas-py requested a review from teemingc July 18, 2026 15:44
Rich-Harris
Rich-Harris approved these changes Jul 20, 2026
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thank you!

@Rich-Harris
Rich-Harris merged commit 5f78e95 into sveltejs:version-3 Jul 20, 2026
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@github-actions github-actions Bot mentioned this pull request Jul 20, 2026
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Rich-Harris pushed a commit that referenced this pull request Jul 24, 2026
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Version Packages (next) (#16435)
c6bfbbd 
This PR was opened by the [Changesets
release](https://github.com/changesets/action) GitHub action. When
you're ready to do a release, you can merge this and the packages will
be published to npm automatically. If you're not ready to do a release
yet, that's fine, whenever you add more changesets to version-3, this PR
will be updated.

⚠️⚠️⚠️⚠️⚠️⚠️

`version-3` is currently in **pre mode** so this branch has prereleases
rather than normal releases. If you want to exit prereleases, run
`changeset pre exit` on `version-3`.

⚠️⚠️⚠️⚠️⚠️⚠️

# Releases
## @sveltejs/kit@3.0.0-next.12

### Major Changes

- breaking: rename `Pathname` type to `Path` and `Asset` to `AssetPath`
([#16430](#16430))
  breaking: remove leading `/` from `Path` and `AssetPath`
- breaking: write tsconfig to `node_modules/$app/tsconfig`
([#16458](#16458))

- breaking: error on `event.url`, `event.params` and `event.route`
access inside queries
([#16452](#16452))

- breaking: delete `$service-worker` module
([#16450](#16450))

- breaking: detect new deployments on data, remote, and form action
responses, tab focus, and visibility change, and default
`version.pollInterval` to 1 hour
([#16496](#16496))

### Minor Changes

- feat: add `$app/manifest` module with `immutable`, `assets`,
`prerendered`, and `routes` exports
([#16372](#16372))

- feat: validate that all remote form fields were created with
form.fields.foo.as(...)
([#16331](#16331))

- feat: make `$app/paths` importable in service workers
([#16441](#16441))

- feat: `$app/service-worker` module
([#16458](#16458))

- feat: better tsconfig validation
([#16458](#16458))

- fix: default cookies to `secure` to `false` during development
([#16462](#16462))

### Patch Changes

- fix: allow `undefined` values to be passed to form field `.as(...)`
where applicable ([#15681](#15681))

- fix: include queries refreshed from within another query in the
serialized response
([#16461](#16461))

- fix: generate sourcemaps for remote modules
([#16440](#16440))

- fix: avoid empty getElementById() call on hash routing navigation
([#16448](#16448))

- fix: warn if hook files are spelled as "hook" instead of "hooks"
([#16483](#16483))

- chore: deprecate the `alias` option
([#16470](#16470))

- fix: prevent infinite loops when server-side queries refresh each
other in a cycle during the single-flight drain
([#16461](#16461))

- fix: populate `version` in service workers
([#16434](#16434))

- fix: resolve remote modules as external during dev prebundling so
packages can re-export remote functions
([#16426](#16426))

- fix: refetch route-tracking server data when navigating away from an
error page ([#16381](#16381))

- fix: serialize `query(...).set(...)`/`query(...).refresh()` values
into the rendered HTML when called from within a query during SSR
([#16461](#16461))

- fix: fall back to the page's form actions when a sibling endpoint has
no POST handler ([#16349](#16349))

- fix: return a lightweight 404 instead of rendering the error page for
subresource requests
([#16463](#16463))

- fix: preserve stripped path prefixes by making trailing-slash
redirects relative
([#16431](#16431))

- chore: deduplicate type-stripping logic in `tweak_types`
([#16454](#16454))

- fix: more informative error message when running a command inside a
query or prerender function
([`eb5c973`](eb5c973))
## @sveltejs/adapter-cloudflare@8.0.0-next.3

### Patch Changes

- chore: bump `@cloudflare/workers-types` to `4.20260621.1`
([#16455](#16455))
- Updated dependencies
[[`adc4c5b`](adc4c5b),
[`ecb0701`](ecb0701),
[`4b4cc60`](4b4cc60),
[`7390dbe`](7390dbe),
[`2e71340`](2e71340),
[`c87bc3a`](c87bc3a),
[`af15c6c`](af15c6c),
[`c6fa431`](c6fa431),
[`bfe4dea`](bfe4dea),
[`df7dc72`](df7dc72),
[`5ae11a1`](5ae11a1),
[`781205c`](781205c),
[`c87bc3a`](c87bc3a),
[`a1bfeb9`](a1bfeb9),
[`c87bc3a`](c87bc3a),
[`9f0127d`](9f0127d),
[`4b4cc60`](4b4cc60),
[`8f5b9c7`](8f5b9c7),
[`c9b5544`](c9b5544),
[`fe1d4a4`](fe1d4a4),
[`4b4cc60`](4b4cc60),
[`5f78e95`](5f78e95),
[`25510fc`](25510fc),
[`c99a6cf`](c99a6cf),
[`17a45ca`](17a45ca),
[`2ca20c3`](2ca20c3),
[`eb5c973`](eb5c973)]:
  - @sveltejs/kit@3.0.0-next.12
## @sveltejs/adapter-netlify@7.0.0-next.4

### Patch Changes

- fix: await `init` on every request to prevent race condition
([#16467](#16467))

- chore: bump Rolldown to `1.2.0`
([#16455](#16455))
- Updated dependencies
[[`adc4c5b`](adc4c5b),
[`ecb0701`](ecb0701),
[`4b4cc60`](4b4cc60),
[`7390dbe`](7390dbe),
[`2e71340`](2e71340),
[`c87bc3a`](c87bc3a),
[`af15c6c`](af15c6c),
[`c6fa431`](c6fa431),
[`bfe4dea`](bfe4dea),
[`df7dc72`](df7dc72),
[`5ae11a1`](5ae11a1),
[`781205c`](781205c),
[`c87bc3a`](c87bc3a),
[`a1bfeb9`](a1bfeb9),
[`c87bc3a`](c87bc3a),
[`9f0127d`](9f0127d),
[`4b4cc60`](4b4cc60),
[`8f5b9c7`](8f5b9c7),
[`c9b5544`](c9b5544),
[`fe1d4a4`](fe1d4a4),
[`4b4cc60`](4b4cc60),
[`5f78e95`](5f78e95),
[`25510fc`](25510fc),
[`c99a6cf`](c99a6cf),
[`17a45ca`](17a45ca),
[`2ca20c3`](2ca20c3),
[`eb5c973`](eb5c973)]:
  - @sveltejs/kit@3.0.0-next.12
## @sveltejs/adapter-node@6.0.0-next.6

### Patch Changes

- fix: preserve stripped path prefixes by making trailing-slash
redirects relative
([#16431](#16431))

- chore: bump Rolldown to `1.2.0`
([#16455](#16455))
- Updated dependencies
[[`adc4c5b`](adc4c5b),
[`ecb0701`](ecb0701),
[`4b4cc60`](4b4cc60),
[`7390dbe`](7390dbe),
[`2e71340`](2e71340),
[`c87bc3a`](c87bc3a),
[`af15c6c`](af15c6c),
[`c6fa431`](c6fa431),
[`bfe4dea`](bfe4dea),
[`df7dc72`](df7dc72),
[`5ae11a1`](5ae11a1),
[`781205c`](781205c),
[`c87bc3a`](c87bc3a),
[`a1bfeb9`](a1bfeb9),
[`c87bc3a`](c87bc3a),
[`9f0127d`](9f0127d),
[`4b4cc60`](4b4cc60),
[`8f5b9c7`](8f5b9c7),
[`c9b5544`](c9b5544),
[`fe1d4a4`](fe1d4a4),
[`4b4cc60`](4b4cc60),
[`5f78e95`](5f78e95),
[`25510fc`](25510fc),
[`c99a6cf`](c99a6cf),
[`17a45ca`](17a45ca),
[`2ca20c3`](2ca20c3),
[`eb5c973`](eb5c973)]:
  - @sveltejs/kit@3.0.0-next.12
## @sveltejs/adapter-vercel@7.0.0-next.3

### Patch Changes

- fix: await `init` on every request to prevent race condition
([#16467](#16467))

- chore: bump Rolldown to `1.2.0`
([#16455](#16455))
- Updated dependencies
[[`adc4c5b`](adc4c5b),
[`ecb0701`](ecb0701),
[`4b4cc60`](4b4cc60),
[`7390dbe`](7390dbe),
[`2e71340`](2e71340),
[`c87bc3a`](c87bc3a),
[`af15c6c`](af15c6c),
[`c6fa431`](c6fa431),
[`bfe4dea`](bfe4dea),
[`df7dc72`](df7dc72),
[`5ae11a1`](5ae11a1),
[`781205c`](781205c),
[`c87bc3a`](c87bc3a),
[`a1bfeb9`](a1bfeb9),
[`c87bc3a`](c87bc3a),
[`9f0127d`](9f0127d),
[`4b4cc60`](4b4cc60),
[`8f5b9c7`](8f5b9c7),
[`c9b5544`](c9b5544),
[`fe1d4a4`](fe1d4a4),
[`4b4cc60`](4b4cc60),
[`5f78e95`](5f78e95),
[`25510fc`](25510fc),
[`c99a6cf`](c99a6cf),
[`17a45ca`](17a45ca),
[`2ca20c3`](2ca20c3),
[`eb5c973`](eb5c973)]:
  - @sveltejs/kit@3.0.0-next.12

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Allow content-negotiation for POST requests too

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