Common pitfalls when migrating large on-premise ETL workflows to Databricks include data compatibility issues, lack of scalability planning, and inefficient resource management. Data transformation logic may need to be rewritten for Spark compatibility. Additionally, performance tuning in a cloud environment can be challenging without proper cost management strategies. To avoid these issues, ensure thorough testing, optimize Spark configurations, and use Delta Lake for efficient data management. Implementing automated scaling and monitoring also helps maintain performance and minimize costs.