[config] Convert path-to-regexp patterns to regex in Route output by MatthewStanciu · Pull Request #15134 · vercel/vercel

MatthewStanciu · 2026-02-19T01:26:15Z

I was digging into a customer-reported issue where a customer's rewrites stopped working when they added a header transform using vercel.ts.

After digging on it I realized that when we don't convert path-to-regexp patterns to proper regex when compiling routes.rewrite() to the routes format. So it gets compiled to this:

{
  "src": "^/api/proxy/:path*$",
  "dest": "https://api.example.com/:path*",
  "transforms": [...]
}

When it should look like this:

{
  "src": "^/api/proxy(?:/((?:[^/]+?)(?:/(?:[^/]+?))*))?$",
  "dest": "https://api.example.com/$1",
}

So the route returns a 404 because it's trying to literally serve :path. This isn't an issue for rewrites defined in the rewrites property of vercel.json because those use the path-to-regexp format. I didn't realize that this differed when writing the logic to convert to routes.

The fix converts patterns using sourceToRegex() from routing-utils when returning routes format.

Note

Low Risk Change

This PR fixes a bug in route pattern conversion by properly transforming path-to-regexp patterns to regex format, which is a correctness fix for routing behavior rather than a security-sensitive change.

Adds sourceToRegex() conversion for route source patterns in rewrite/redirect logic
New convertDestination() helper replaces named params with capture group references
Test expectations updated to reflect proper regex output format

^{Risk assessment for commit 312e2c8.}

changeset-bot · 2026-02-19T01:26:21Z

🦋 Changeset detected

Latest commit: 312e2c8

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

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Name	Type
@vercel/config	Patch

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github-actions · 2026-02-19T01:26:44Z

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github-actions · 2026-02-19T01:27:43Z

🧪 Unit Test Strategy

Comparing: 2cfc724 → 312e2c8 (view diff)

Strategy: Code changed outside of a package - running all unit tests

⚠️ All unit tests will run because global code changes could impact all packages.

Affected packages - 16 (40%)

@vercel/config
@vercel/build-utils
@vercel/client
@vercel/firewall
@vercel/fs-detectors
@vercel/go
@vercel/hydrogen
@vercel/next
@vercel/node
@vercel/python
@vercel/remix-builder
@vercel/ruby
@vercel/rust
@vercel/static-build
examples
vercel

Unaffected packages - 24 (60%)

@vercel-internals/get-package-json
@vercel/backends
@vercel/cervel
@vercel/cli-auth
@vercel/detect-agent
@vercel/edge
@vercel/elysia
@vercel/error-utils
@vercel/express
@vercel/fastify
@vercel/frameworks
@vercel/functions
@vercel/gatsby-plugin-vercel-builder
@vercel/h3
@vercel/hono
@vercel/koa
@vercel/nestjs
@vercel/oidc
@vercel/oidc-aws-credentials-provider
@vercel/python-analysis
@vercel/redwood
@vercel/related-projects
@vercel/routing-utils
@vercel/static-config

Results

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E2E tests: Running in parallel via E2E Tests workflow
Type checks: All affected packages will run type checks

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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 publish to npm yourself or [setup this action to publish automatically](https://github.com/changesets/action#with-publishing). If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## vercel@50.21.0 ### Minor Changes - Add `--all` flag to `vercel ls` command and improve behavior when not linked to a project ([#15143](#15143)) - `vercel ls` no longer requires a linked project. When not linked, it now lists all deployments across all projects in the current scope - Added `--all` flag to explicitly list deployments across all projects, even when linked to a specific project - Added "Project" column to the deployment table output to show which project each deployment belongs to - JSON output (`--format json`) is unchanged and continues to include the `name` field for project name ### Patch Changes - fix(cli): Handle SIGINT during upgrade prompt without showing a stacktrace ([#15105](#15105)) - Use formatted tables for `metrics schema` output, matching the convention used by other list commands ([#15138](#15138)) - Updated dependencies \[[`5d1f55af04d0fdba7e7ac86f9eeda44316f54f5b`](5d1f55a)]: - @vercel/next@4.15.31 ## @vercel/config@0.0.33 ### Patch Changes - Fix rewrite regexp conversion when header transforms are present ([#15134](#15134)) ## @vercel/next@4.15.31 ### Patch Changes - Added support for `regions` and `functionFailoverRegions` in per-function configuration from `vercel.json` for Next.js projects. ([#15149](#15149)) ## @vercel/python-runtime@0.4.3 ### Patch Changes - fix formatting and lint ([#15142](#15142))  > [!NOTE] > Low Risk Change > > This PR is an automated Changesets release that only bumps version numbers in package.json files, updates CHANGELOG.md files, and deletes changeset markdown files - no code logic changes. > > - Version bumps in package.json files (vercel, @vercel/config, @vercel/next, @vercel/python-runtime) > - CHANGELOG.md updates documenting previous changes > - Deleted .changeset/*.md files consumed by release process > > <sup>Risk assessment for [commit 3b54c69](https://github.com/vercel/vercel/commit/3b54c6956719db3f1dfd50629330f42ab8143af6).</sup>  Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

The previous fix (#15134) only addressed pattern conversion when rewrite() and redirect() methods returned Route objects with transforms or env vars. This fix extends the conversion to the getConfig() method, which converts redirects, rewrites, and headers to routes format when routes are present. Without this fix, patterns like `:path*` would be passed through literally instead of being converted to proper regex, causing 404 errors. https://claude.ai/code/session_01CeTsDHjUb1wrKjMEBCsv87

[config] Convert path-to-regexp patterns to regex in Route output

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vercel bot deployed to Preview February 19, 2026 01:26 View deployment

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vercel bot deployed to Preview February 19, 2026 01:53 View deployment

Merge branch 'main' into matthew/convert-routes-regexp

312e2c8

MatthewStanciu marked this pull request as ready for review February 19, 2026 01:54

MatthewStanciu requested a review from a team as a code owner February 19, 2026 01:54

vercel bot deployed to Preview February 19, 2026 01:54 View deployment

ali-vercel approved these changes Feb 19, 2026

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MatthewStanciu merged commit 50f1d5d into main Feb 19, 2026
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MatthewStanciu deleted the matthew/convert-routes-regexp branch February 19, 2026 19:17

vercel-release-bot mentioned this pull request Feb 19, 2026

Version Packages #15150

Merged

mitul-s mentioned this pull request Feb 22, 2026

fix(config): convert path-to-regexp patterns to regex in getConfig() #15203

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[config] Convert path-to-regexp patterns to regex in Route output#15134

[config] Convert path-to-regexp patterns to regex in Route output#15134
MatthewStanciu merged 3 commits intomainfrom
matthew/convert-routes-regexp

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