There have been several serialization bug reports from the 2021.03.1 release (see dask/distributed#4645, dask/distributed#4625, dask/dask#7490) which we're currently resolving (xref dask/distributed#4653). I'd like to do a dask and distributed 2021.04.0 release this Friday to get those fixes out to users.

cc @jakirkham @kkraus14 @jsignell