Commercial nuget server lists some non existing packages which causes dotnet restore to fail. Please remove these packages from the nuget server listing
/usr/share/dotnet/sdk/3.1.102/NuGet.targets(123,5): error : The feed 'https://nuget.abp.io/secret/v3/index.json lists package 'Microsoft.Extensions.Hosting.Abstractions.3.0.0' but multiple attempts to download the nupkg have failed. The feed is either invalid or required packages were removed while the current operation was in progress. Verify the package exists on the feed and try again.