data_dir cannot be empty

[hacxxx]

I'm in the midst of upgrading my consul from version 0.5.2 to the latest 1.4.3. While trying to validate the old config file which was named "consul.conf" using "consul validate" of version 1.4.3, I found the file extension has to be renamed to "consul.json" instead. This is all fine except that the consul validate tool returned something that I scratched my head for quite a bit.

consul validate consul.conf

Config validation failed: data_dir cannot be empty

I do have data_dir defined in my config file. The reported error just does not reflect reality. After renaming the file to "consul.json", it verified fine.