> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.getunleash.io/api/release-templates/change-milestone-progression/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.getunleash.io/_mcp/server.

# Create or update a milestone progression

PUT https://app.unleash-instance.example.com/api/admin/projects/{project}/features/{featureName}/environments/{environment}/progressions/{id}
Content-Type: application/json

**Enterprise feature**

Creates or updates a milestone progression by source milestone ID. If a progression with the given source milestone exists, it will be updated; otherwise, a new one will be created.

Reference: https://docs.getunleash.io/api/release-templates/change-milestone-progression

## Authentication

- `Authorization` header (required) — API key needed to access this API
- `Authorization` header (bearer token, required) — API key needed to access this API, in Bearer token format

## Request

### Path parameters

- `project` (string, required)
- `featureName` (string, required)
- `environment` (string, required)
- `id` (string, required)

### Body (application/json)

This endpoint expects a changeMilestoneProgressionSchema.

- `targetMilestone` (string, required) — The ID of the target milestone
- `transitionCondition` (transitionConditionSchema, required) — The condition configuration for the transition

## Response

### 200

#/components/schemas/milestoneProgressionSchema

- `sourceMilestone` (string, required) — The ID of the source milestone
- `targetMilestone` (string, required) — The ID of the target milestone
- `transitionCondition` (transitionConditionSchema, required) — The condition that triggers the transition

## Errors

### 401 Unauthorized Error

Authorization information is missing or invalid. Provide a valid API token as the `authorization` header, e.g. `authorization:*.*.my-admin-token`.

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

### 403 Forbidden Error

The provided user credentials are valid, but the user does not have the necessary permissions to perform this operation

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

## Types

### transitionConditionSchema

A transition condition for milestone progression

### TransitionConditionSchema0

Transition after a fixed amount of time from milestone start

- `intervalMinutes` (integer, required) — The interval in minutes before transitioning
- `type` (enum, optional) — Discriminator for time-based transitions. Omitting it means time-based.
  - Allowed values: `time`

### TransitionConditionSchema1

Transition once the feature has been exposed (evaluated as enabled) enough times in total

- `type` (enum, required) — Discriminator for exposure-based transitions
  - Allowed values: `exposure`
- `minimumExposures` (integer, required) — The total number of enabled evaluations of the feature required before transitioning

## Examples

**Request**

```json
{
  "targetMilestone": "11K7NXD655W7R89659K58RE07B",
  "transitionCondition": {
    "intervalMinutes": 30,
    "type": "time"
  }
}
```

**Response**

```json
{
  "sourceMilestone": "milestone-1",
  "targetMilestone": "milestone-2",
  "transitionCondition": {
    "intervalMinutes": 30,
    "type": "time"
  }
}
```

**SDK Code**

```python
import requests

url = "https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id"

payload = {
    "targetMilestone": "11K7NXD655W7R89659K58RE07B",
    "transitionCondition": {
        "intervalMinutes": 30,
        "type": "time"
    }
}
headers = {
    "Authorization": "<apiKey>",
    "Content-Type": "application/json"
}

response = requests.put(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id';
const options = {
  method: 'PUT',
  headers: {Authorization: '<apiKey>', 'Content-Type': 'application/json'},
  body: '{"targetMilestone":"11K7NXD655W7R89659K58RE07B","transitionCondition":{"intervalMinutes":30,"type":"time"}}'
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id"

	payload := strings.NewReader("{\n  \"targetMilestone\": \"11K7NXD655W7R89659K58RE07B\",\n  \"transitionCondition\": {\n    \"intervalMinutes\": 30,\n    \"type\": \"time\"\n  }\n}")

	req, _ := http.NewRequest("PUT", url, payload)

	req.Header.Add("Authorization", "<apiKey>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Put.new(url)
request["Authorization"] = '<apiKey>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"targetMilestone\": \"11K7NXD655W7R89659K58RE07B\",\n  \"transitionCondition\": {\n    \"intervalMinutes\": 30,\n    \"type\": \"time\"\n  }\n}"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.put("https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id")
  .header("Authorization", "<apiKey>")
  .header("Content-Type", "application/json")
  .body("{\n  \"targetMilestone\": \"11K7NXD655W7R89659K58RE07B\",\n  \"transitionCondition\": {\n    \"intervalMinutes\": 30,\n    \"type\": \"time\"\n  }\n}")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('PUT', 'https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id', [
  'body' => '{
  "targetMilestone": "11K7NXD655W7R89659K58RE07B",
  "transitionCondition": {
    "intervalMinutes": 30,
    "type": "time"
  }
}',
  'headers' => [
    'Authorization' => '<apiKey>',
    'Content-Type' => 'application/json',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id");
var request = new RestRequest(Method.PUT);
request.AddHeader("Authorization", "<apiKey>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"targetMilestone\": \"11K7NXD655W7R89659K58RE07B\",\n  \"transitionCondition\": {\n    \"intervalMinutes\": 30,\n    \"type\": \"time\"\n  }\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "<apiKey>",
  "Content-Type": "application/json"
]
let parameters = [
  "targetMilestone": "11K7NXD655W7R89659K58RE07B",
  "transitionCondition": [
    "intervalMinutes": 30,
    "type": "time"
  ]
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://app.unleash-instance.example.com/api/admin/projects/project/features/featureName/environments/environment/progressions/id")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "PUT"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```