The document details the challenges and solutions associated with upgrading from Python 2 to Python 3, emphasizing the importance of this transition due to Python 2's end of support in 2020. It highlights incompatibilities between the two versions, such as differences in syntax and handling of data types, and describes a three-step porting process involving auto-conversion, manual changes, and runtime validation. The text illustrates these differences through specific examples and solutions, including the use of tools like the 2to3 conversion utility and the deepdiff module for object comparison. It also provides a detailed comparison of Python 2 and 3 features, aiming to assist developers in navigating common migration issues. By sharing Couchbase's experience in migrating their TestRunner framework, the document serves as a practical guide for developers facing similar challenges.