curl --request POST \
  --url https://api.hubapi.com/marketing/marketing-events/2026-03/events/upsert \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "inputs": [
    {
      "customProperties": [
        {
          "isEncrypted": true,
          "isLargeValue": true,
          "name": "<string>",
          "persistenceTimestamp": 123,
          "requestId": "<string>",
          "selectedByUser": true,
          "selectedByUserTimestamp": 123,
          "sourceId": "<string>",
          "sourceLabel": "<string>",
          "sourceMetadata": "<string>",
          "sourceUpstreamDeployable": "<string>",
          "sourceVid": [
            123
          ],
          "timestamp": 123,
          "unit": "<string>",
          "updatedByUserId": 123,
          "useTimestampAsPersistenceTimestamp": true,
          "value": "<string>"
        }
      ],
      "eventName": "<string>",
      "eventOrganizer": "<string>",
      "externalAccountId": "<string>",
      "externalEventId": "<string>",
      "endDateTime": "2023-11-07T05:31:56Z",
      "eventCancelled": true,
      "eventCompleted": true,
      "eventDescription": "<string>",
      "eventType": "<string>",
      "eventUrl": "<string>",
      "startDateTime": "2023-11-07T05:31:56Z"
    }
  ]
}
'

{
  "completedAt": "2023-11-07T05:31:56Z",
  "results": [
    {
      "createdAt": "2023-11-07T05:31:56Z",
      "customProperties": [
        {
          "isEncrypted": true,
          "isLargeValue": true,
          "name": "<string>",
          "persistenceTimestamp": 123,
          "requestId": "<string>",
          "selectedByUser": true,
          "selectedByUserTimestamp": 123,
          "sourceId": "<string>",
          "sourceLabel": "<string>",
          "sourceMetadata": "<string>",
          "sourceUpstreamDeployable": "<string>",
          "sourceVid": [
            123
          ],
          "timestamp": 123,
          "unit": "<string>",
          "updatedByUserId": 123,
          "useTimestampAsPersistenceTimestamp": true,
          "value": "<string>"
        }
      ],
      "eventName": "<string>",
      "eventOrganizer": "<string>",
      "id": "<string>",
      "updatedAt": "2023-11-07T05:31:56Z",
      "endDateTime": "2023-11-07T05:31:56Z",
      "eventCancelled": true,
      "eventCompleted": true,
      "eventDescription": "<string>",
      "eventType": "<string>",
      "eventUrl": "<string>",
      "objectId": "<string>",
      "startDateTime": "2023-11-07T05:31:56Z"
    }
  ],
  "startedAt": "2023-11-07T05:31:56Z",
  "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"
}