When using GO with Remote Repository in Artifactory, Artifactory returns a 404 error on certain packages although they exists on the sources.
Since VGO client is quite new, it's expecting a go.mod file in a Go project (and its dependencies) during package resolution, some packages may not contain this file, therefore, results with a 404 error.
Right after the 404 response, the VGO client will create it (since the creation of the file is not under Artifactory scope).
This is something that will be resolved with time in newer versions. The current workaround, is to build using VGO without the GOPROXY environment variable set.
Once done, VGO will create a go.mod file upon deployment to Artifactory. Once the file is created, you may re-enable the GOPROXY environment variable.