Update a milestone

Change a milestone's title, description, due date or state (open or closed); only the fields given change, and due_on "" clears its due date.

PATCH/repos/{owner}/{name}/milestones/{milestone}

Needs the Write role or higher; applying labels and milestones needs Triage.

Authentication: Required. Send an access token as Authorization: Bearer.
MCP tool: repository with action update_milestone, and the same inputs
Scope: An access token needs issues:write.

Path parameters

Name	Type	Required	Description
`owner`	string	Yes	The workspace that owns the repository.
`name`	string	Yes	The repository’s name.
`milestone`	integer	Yes	The milestone’s number, from `list_milestones`.

Body parameters

Send a JSON object. Names are snake_case, as in responses; the camelCase spelling is accepted too.

Name	Type	Required	Description
`title`	string	No	Unique in the repository, at most 100 characters.
`description`	string	No	Markdown.
`due_on`	string	No	The day it is due, YYYY-MM-DD. On update, “” clears it.
`state`	string	No	One of `open`, `closed`.

Example request

curl -X PATCH https://api.g1t.sh/repos/flagon-io/hello/milestones/3 \
  -H "Authorization: Bearer $G1T_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "state": "closed"
  }'

Example response

A successful request answers 200 with:

{
  "number": 3,
  "title": "Launch",
  "description": "Everything that has to land before the launch on October 14.",
  "due_on": "2026-10-14",
  "state": "closed",
  "open_items": 0,
  "closed_items": 17,
  "created_at": "2026-09-20T09:00:00.000Z",
  "updated_at": "2026-10-14T18:00:00.000Z",
  "closed_at": "2026-10-14T18:00:00.000Z"
}

Errors

A failed request answers with one of these statuses and a body like {"error": {"code": "not_found", "message": "Repository not found."}}. See errors.

Status	Code	When
401	`unauthenticated`	A token is required, or the one sent is not valid.
403	`forbidden`	The token is valid but not allowed to do this, such as a member-only change or an agent token outside its repository.
404	`not_found`	It does not exist, or you cannot see it.
409	`conflict`	The request conflicts with the current state.
422	`invalid`	The input is not valid. `message` says which field and why.