curl --request POST \
  --url https://commet.co/api/v1/subscriptions/{id}/change-version \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "planVersionId": "<string>"
}
'

const options = {
  method: 'POST',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({planVersionId: '<string>'})
};

fetch('https://commet.co/api/v1/subscriptions/{id}/change-version', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://commet.co/api/v1/subscriptions/{id}/change-version"

payload = { "planVersionId": "<string>" }
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

package main

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

func main() {

	url := "https://commet.co/api/v1/subscriptions/{id}/change-version"

	payload := strings.NewReader("{\n  \"planVersionId\": \"<string>\"\n}")

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

	req.Header.Add("x-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://commet.co/api/v1/subscriptions/{id}/change-version")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"planVersionId\": \"<string>\"\n}")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://commet.co/api/v1/subscriptions/{id}/change-version",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'planVersionId' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

{
  "id": "sub_1a2b3c4d",
  "customerId": "cus_1a2b3c4d",
  "plan": {
    "id": "plan_1a2b3c4d",
    "name": "Pro",
    "basePrice": 2000
  },
  "planVersion": {
    "id": "plr_1a2b3c4d",
    "label": "3"
  },
  "scheduledVersionChange": {
    "planVersionId": "plr_9i0j1k2l",
    "label": "4",
    "effectiveAt": "2026-10-07T12:00:00.000Z"
  },
  "name": "Pro",
  "description": null,
  "status": "active",
  "billingInterval": "monthly",
  "trialEndsAt": null,
  "currentPeriod": {
    "start": "2026-09-07T12:00:00.000Z",
    "end": "2026-10-07T12:00:00.000Z",
    "daysRemaining": 30
  },
  "cancellation": null,
  "cancelAtPeriodEnd": false,
  "scheduledPlanChange": null,
  "startDate": "2026-09-07T12:00:00.000Z",
  "endDate": null,
  "billingDayOfMonth": 7,
  "nextBillingDate": "2026-10-07T12:00:00.000Z",
  "checkoutUrl": null,
  "createdAt": "2026-09-07T12:00:00.000Z",
  "updatedAt": "2026-09-07T12:00:00.000Z",
  "offerApplications": [],
  "pause": null,
  "priceId": "price_1a2b3c4d",
  "object": "subscription",
  "livemode": false,
  "consumptionModel": "metered",
  "features": [
    {
      "code": "api_calls",
      "name": "API Calls",
      "type": "usage",
      "usage": {
        "current": 250,
        "included": 1000,
        "overageQuantity": 0,
        "unlimited": false
      }
    }
  ],
  "credits": null,
  "balance": null
}

{
  "error": {
    "type": "validation_error",
    "code": "validation_error",
    "message": "The request contains an invalid parameter.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/validation_error.md"
  }
}

{
  "error": {
    "type": "authentication_error",
    "code": "unauthorized",
    "message": "A valid API key is required.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/unauthorized.md"
  }
}

{
  "error": {
    "type": "authentication_error",
    "code": "forbidden",
    "message": "You do not have permission to perform this operation.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/forbidden.md"
  }
}

{
  "error": {
    "type": "not_found_error",
    "code": "not_found",
    "message": "The requested resource was not found.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/not_found.md"
  }
}

{
  "error": {
    "type": "conflict_error",
    "code": "idempotency_in_progress",
    "message": "A request with this idempotency key is still being processed.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_in_progress.md"
  }
}

{
  "error": {
    "type": "validation_error",
    "code": "validation_error",
    "message": "The requested operation is not valid for the current configuration.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/validation_error.md"
  }
}

{
  "error": {
    "type": "rate_limit_error",
    "code": "rate_limited",
    "message": "Too many requests. Retry after the interval specified in the Retry-After header.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/rate_limited.md"
  }
}

{
  "error": {
    "type": "internal_error",
    "code": "internal_error",
    "message": "An unexpected error occurred while processing the request.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/internal_error.md"
  }
}

{
  "error": {
    "type": "internal_error",
    "code": "idempotency_unavailable",
    "message": "Idempotency storage is temporarily unavailable. Retry with the same idempotency key.",
    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_unavailable.md"
  }
}