When you create a Databricks Runtime 5.5 LTS cluster by using the workspace UI, the default is Python 3. You have the option to specify Python 2. If you use the Databricks REST API to create a cluster using Databricks Runtime 5.5 LTS, the default is Python 2. If you have a Databricks Runtime 5.5 LTS cluster running Python 2, you are not required to upgrade to Python 3.