Between legacy code that has been around for N years jumping from developer to developer with no documentation. To over complicated interfaces that are over complicating the code. To a mixture of N technologies in one single app. Lets face it, these things were not built with maintainability and support in mind. The problem we face today is, how do we fix all these apps? Where do we start? How do we bring sanity into them? How do we bring them into state of the art tech stacks?