| ERROR | user_data type and queue type do not match |
| CAUSE | A user tries to enqueue an object to a queue that was created for objects of different type. |
| ACTION | Try enqueue again with an object of the right type. |
| ERROR | user_data type and queue type do not match |
| CAUSE | A user tries to enqueue an object to a queue that was created for objects of different type. |
| ACTION | Try enqueue again with an object of the right type. |