I get the same error when using a theme via modules. I have no problem getting the theme working, but when I try to run hugo mod get -u, I get that error message referring to my project path.
tom@ladybird exampleSite$ hugo mod get -u
go get .: path /mnt/c/Users/Tom/Sync/home/exampleSite is not a package in module rooted at /mnt/c/Users/Tom/Sync/home/exampleSite
I’m reading all I can about Go modules, but I’d definitely appreciate being pointed in the right direction so I can figure this out faster.
I followed the steps here: Hugo modules for "dummies" and then I get the error when trying to update modules.
go version go1.13.4 linux/amd64