0.x — pre-release, no compatibility promise yet.What this means
Create a milestone
Create an open milestone. edit on the team. 409 on a duplicate live title (open or
closed), 422 when the owner is not an active member of this team.
Authorizations
Section titled “Authorizations”Parameters
Section titled “ Parameters ”Path Parameters
Section titled “Path Parameters”Request Bodyrequired
Section titled “Request Bodyrequired”The request body of milestones.create.
object
Unique among the team’s live milestones, open or closed (case-insensitive) — 409 otherwise
The date the team commits to. Passing it changes nothing; the view shows it as overdue.
Example
{ "title": "string", "target_date": "2026-09-25", "description": "string", "owner_user_id": "string"}Responses
Section titled “ Responses ”Successful Response
Returned by milestones.create and milestones.update.
object
Tasks filed under this milestone (every status, subtasks excluded).
How many of them are completed — the roll-up’s done against total.
Example
{ "milestone_id": "string", "org_id": "string", "team_id": "string", "title": "string", "target_date": "2026-09-25", "description": "string", "owner_user_id": "string", "status": "open", "closed_at": "2026-09-25T12:00:00Z", "closed_by": "string", "created_by": "string", "updated_by": "string", "created_at": "2026-09-25T12:00:00Z", "updated_at": "2026-09-25T12:00:00Z", "is_active": true, "stop_id": "string", "task_count": 0, "completed_count": 0}Bad request — a query parameter outside what the operation accepts (invalid-parameter)
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Bad request", "status": 400, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}Missing or invalid bearer token
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Missing or invalid bearer token", "status": 401, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}Authenticated, but not allowed
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Authenticated, but not allowed", "status": 403, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}Not found
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Not found", "status": 404, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}Conflict (a duplicate, or an Idempotency-Key still in flight)
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Conflict (a duplicate, or an `Idempotency-Key` still in flight)", "status": 409, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}If-Match does not match the current ETag
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "`If-Match` does not match the current `ETag`", "status": 412, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}The body or query did not validate (validation), or an Idempotency-Key was reused
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "The body or query did not validate (`validation`), or an `Idempotency-Key` was reused", "status": 422, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}An access token over its per-minute limit (rate-limit; see Retry-After)
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "An access token over its per-minute limit (`rate-limit`; see `Retry-After`)", "status": 429, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}Unexpected server error — quote request_id
An RFC 9457 problem details object — the body of every error response. detail is the human-readable explanation; request_id identifies the request for support.
object
about:blank or a urn:tasksmate:problem:* identifier
Human-readable explanation (a string; for a 422, the list of validation errors)
Structured failures: validation errors, or {loc, msg, allowed} for a bad parameter
object
Example
{ "type": "about:blank", "title": "Unexpected server error", "status": 500, "detail": "…", "instance": "/v1/…", "request_id": "9b2f1c1e-8c1a-4a53-9f9e-0f5f1f2d7c11"}