编译报错请问是什么原因呢

[hahaSec]

λ go build main.go main.go:7:2: cannot find package "github.com/urfave/cli/v2" in any of: D:\Program Files (x86)\Go\src\github.com\urfave\cli\v2 (from $GOROOT) λ go get github.com/urfave/cli/v2 package github.com/urfave/cli/v2: cannot find package "github.com/urfave/cli/v2" in any of: D:\Program Files (x86)\Go\src\github.com\urfave\cli\v2 (from $GOROOT)

[CTF-MissFeng]

λgo build main.go main.go：7：2：在以下任何位置都找不到软件包“ github.com/urfave/cli/v2”： D：\ Program Files（x86）\ Go \ src \ github.com \ urfave \ cli \ v2（来自$ GOROOT） λ获取github.com/urfave/cli/v2 软件包github.com/urfave/cli/v2：在以下任一位置都找不到软件包“ github.com/urfave/cli/v2”： D：\ Program Files（x86）\ Go \ src \ github.com \ urfave \ cli \ v2（来自$ GOROOT）

未找到包路径，详情请查看go的包下载