The "unknown blob" error can be seen when users attempt to pull Docker images via a remote repository that is mirroring an ACR (Azure Container Registry) based registry. A common example is proxying mcr.microsoft.com.
This error occurs due to ACR expecting to receive a request to a URL containing double slash '//' , which is not a standard URL, and therefore Artifactory fails to cache the layers and serve these to the docker client.
In order to resolve this issue, you'll need to disable URL normalization for the affected remote repository (as mentioned in this article).
To do that, navigate in Artifactory to Administration-> Repositories -> the affected remote repository-> Advanced -> and check the “Disable URL Normalization” checkbox.
Keywords: mcr.microsoft.com