Failed to pull image with x509: certificate signed by unknown authority error when using mirrored registries in OpenShift 4

Issue

• Using a mirrored registry, there are pods in ImagePullBackOff error, and the images cannot be pulled with error Failed to pull image and x509: certificate signed by unknown authority error errors.

• The image pull fails with the following message shown in the events:

  Failed to pull image "quay.io/openshift-release-dev/ocp-release@sha256:xxxxxx": rpc error: code = Unknown desc = (Mirrors also failed: custom-image-registry-mirror.example.com:[port]/[namespace]0@sha256:xxxxxx: pinging container registry custom-image-registry-mirror.example.com:[port]: Get "https://custom-image-registry-mirror.example.com:[port]/v2/": x509: certificate signed by unknown authority]): quay.io/openshift-release-dev/ocp-release@sha256:xxxxxx: pinging container registry quay.io: Get "https://quay.io/v2/": dial tcp: lookup quay.io on 10.0.0.1:53: server misbehaving