The exception logger no longer logs errors. Instead it transforms the errors into a grpc friendly format. The exception that would have been logged at this point gets logged when the task completes.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.
Generate proto
grpc_tools_ruby_protoc -I . --ruby_out=gen/plugin --grpc_out=gen/plugin ./plugin_server.proto