We are in process of making some major updates to the caching in BiocFileCache, AnnotationHub, and ExperimentHub. Namely, the default caching location will change from using rappdirs::user_cache_dir to using tools::R_user_dir eventually relieving the dependency on rappdirs. To avoid conflicting default caches, if anyone used an old default caching directory, there will be an error to decide how to deal with the old location before proceeding and documentation in the vignettes for how to resolve. Currently I have update BiocFileCache, the changes were just pushed to the devel branch and should propagate tonight. I plan on doing the same for both AnnotationHub and ExperimentHub within the next few days. We appreciate any feedback or questions with regards to these updates.
This is only relevant to using the default cache location, if a user manually specified a unique location, used environment variables, or created a package specific cache the code/location is not affected. Anyone using package specific caching that utilizes rappdirs is encouraged also to consider changing package code to use the now available function in tools.