src/app/services/api/upload.ts

@@ -35,7 +35,8 @@ export class Upload {
 
  for (let key in data) {
  if (data[key] !== null) {
- formData.append(key, data[key]);
+ const field = typeof data[key] == 'object' ? JSON.stringify(data[key]) : data[key];
+ formData.append(key, field);
  }
  }