I got this error when trying to build a Vapor project.
$ vapor build No .build folder, fetch may take a while... Fetching Dependencies [ • ] Error: backgroundExecute(code: 1, error: "warning: \'fetch\' command is deprecated; use \'resolve\' instead\nerror: root manifest not found\n", output: "")
I recently experienced a lot of error with getting Vapor 3.0 to run during the beta and Swift 4.1. I assumed the error had to do with that. Had I read closer I might have figured it out. I was not in the build directory. Duh! After changing to the build directory everything worked fine.
If you end up on this page, make sure you are in the build directory when trying to build a Vapor project.