# POST /api/v1/project/:username/:repo/tree/:branch is deprecated

Calls to POST /api/v1/project/:username/:repo/tree/:branch on CircleCI API stop working on February 1, 2027.

On February 1, 2027, the endpoint POST /api/v1/project/:username/:repo/tree/:branch will be removed. Requests made to this endpoint will fail after that date. Any integration or workflow relying on this call must update to a supported pipeline trigger endpoint.

- API: CircleCI API (circleci.com)
- Kind: Endpoint removal
- Announced: October 7, 2026
- Takes effect: February 1, 2027
- Calls after that day: fail
- Calls it hits: `POST /api/v1/project/:username/:repo/tree/:branch`
- Source: [Changelog](https://circleci.com/changelog/)
- Page: https://www.okapi.bot/providers/circleci-api/breaking-changes/post-api-v1-project-username-repo-tree-branch-is-deprecated/

## What to use instead

To trigger a pipeline, switch to POST /api/v3/runs in API v3 or POST /api/v2/project/:provider/:organization/:project/pipeline/run in API v2.

## CircleCI API's words

> POST /api/v1/project/:username/:repo/tree/:branch