curl --request PUT \
  --url https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId} \
  --header 'Authorization: Bearer <token>'

import requests

url = "https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}"

headers = {"Authorization": "Bearer <token>"}

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

print(response.text)

const options = {method: 'PUT', headers: {Authorization: 'Bearer <token>'}};

fetch('https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PUT",
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>"
  ],
]);

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

curl_close($curl);

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

package main

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

func main() {

	url := "https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}"

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

	req.Header.Add("Authorization", "Bearer <token>")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.put("https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}")
  .header("Authorization", "Bearer <token>")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.hubapi.com/crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/default/{toObjectType}/{toObjectId}")

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

request = Net::HTTP::Put.new(url)
request["Authorization"] = 'Bearer <token>'

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

{
  "completedAt": "2023-11-07T05:31:56Z",
  "results": [
    {
      "associationSpec": {
        "associationCategory": "HUBSPOT_DEFINED",
        "associationTypeId": 123
      },
      "from": {
        "id": "<string>"
      },
      "to": {
        "id": "<string>"
      }
    }
  ],
  "startedAt": "2023-11-07T05:31:56Z",
  "status": "CANCELED",
  "errors": [
    {
      "category": "<string>",
      "context": {},
      "errors": [
        {
          "message": "<string>",
          "code": "<string>",
          "context": "{missingScopes=[scope1, scope2]}",
          "in": "<string>",
          "subCategory": "<string>"
        }
      ],
      "links": {},
      "message": "<string>",
      "status": "<string>",
      "id": "<string>",
      "subCategory": {}
    }
  ],
  "links": {},
  "numErrors": 123,
  "requestedAt": "2023-11-07T05:31:56Z"
}

{
  "message": "Invalid input (details will vary based on the error)",
  "correlationId": "aeb5f871-7f07-4993-9211-075dc63e7cbf",
  "category": "VALIDATION_ERROR",
  "links": {
    "knowledge-base": "https://www.hubspot.com/products/service/knowledge-base"
  }
}