@Prasanth KP​ ,

• remove comma after XXXXXXX",
• remove "git_source": null
• in ADF, I had to wrap everything in single quotes
• Please test your API call with curl or postman first.

'{
  "tasks": [
    {
      "task_key": "Match",
      "description": "Matches orders with user sessions",
      "notebook_task": {
        "notebook_path": "/Users/userxxx@xxxxsandbox.com/Demo/RealTimeXXXXXXX"
      },
      "timeout_seconds": 86400
    }
  ],
  "run_name": "A multitask job run",
  "timeout_seconds": 86400
}'