My vapor 4.0.0 xCode 11.4 web server runs fine on localhost:8080. When I check the vapor version at the command line, I get 3.1.10, and when I try to deploy, it fails:
$ vapor version
Vapor Toolbox: 3.1.10
$ swift --version
Apple Swift version 5.2 (swiftlang-1103.0.32.1 clang-1103.0.32.29)
Target: x86_64-apple-darwin19.4.0
$ vapor cloud deploy
app: pg3a
...
Selected swift version: 5.2.0 [Failed]
Swift version 5.2.0 is not supported
Error: deploy failed