Problems pushing manifest to insecure registry

Attempting to ‘docker manifest push --insecure’ results in:
failed to configure transport: error pinging v2 registry: Get https://:5000/v2/: http: server gave HTTP response to HTTPS client

OS Version:
$ cat /etc/centos-release
CentOS Linux release 7.3.1611 (Core)

App Version:
$ docker --version
Docker version 18.09.0, build 4d60db4

Steps to reproduce:
docker manifest inspect --insecure mspldocker01:5000/suse/sles15:latest { "schemaVersion": 2, "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json", "manifests": [ { "mediaType": "application/vnd.docker.distribution.manifest.v2+json", "size": 944, "digest": "sha256:7cb1380509ae8a0eba5b088fc949a1c2f33e2cb2c7ca8c30fed14b15ecf60953", "platform": { "architecture": "arm64", "os": "linux" } }, { "mediaType": "application/vnd.docker.distribution.manifest.v2+json", "size": 1154, "digest": "sha256:5b2f1e92d8df9592da8b6693eafbd17b4c0670eb698537df8f73495a88f7e81d", "platform": { "architecture": "amd64", "os": "linux" } } ] } docker manifest push --insecure mspldocker01:5000/suse/sles15:latest
failed to configure transport: error pinging v2 registry: Get https://:5000/v2/: http: server gave HTTP response to HTTPS client