Version Not Found

github.com/fzdarsky/openshift-apiserver v4.0.0-alpha.0+incompatible

The requested version v4.0.0-alpha.0+incompatible cannot be found for package github.com/fzdarsky/openshift-apiserver. Go to the default version (v0.0.0-alpha.0.0.20190731071921-1df757074ad4) instead.