Your server is configured to disable the use of .NET's MD5 processing libraries, which means ProGet cannot read or write Maven index files. You can disable this at the server level: https://www.schneider-electric.com/en/faqs/FA282064/ You can also edit the configuration file; https://docs.microsoft.com/en-us/dotnet/framework/configure-apps/file-schema/runtime/enforcefipspolicy-element

Thanks. FYI: Retention policies should be ignored on free versions. But UNKNOWN does indicate the service user; so it's likely a retention policy job (which is run as part of feed cleanup). You can see the logs of those, and maybe see some more info...