Upgrading from older versions
If you are upgrading from 4.2.x or earlier, make sure you have installed the required dependencies.
If you are having problems upgrading, try to delete the AstarPathfindingProject folder in Unity and import the package again. This can help removing old scripts which are not included in the project anymore but since UnityPackages merges directories, they are still there.
If you have problems with some compiler messages saying that some members or functions do not exist in a class. It is likely that your project contains a class with that name in the global namespace. This causes a conflict between the classes. To solve it, the simplest solution is to put the conflicting class in a namespace or just rename it.