.NET Core 2.1 container images were deleted from Docker Hub!

If you started receiving errors when pulling old versions of dotnet docker images (like the .NET 2.1), it's because Microsoft deleted them from Docker Hub on August 21st, 2021. That date is not a coincidence, the .NET Core 2.1 reached end of support in the same date. For more details take a look at the official dotnet announcement or also the dotnet blog.

In my case, the error below was thrown when pulling the microsoft/dotnet:2.2-aspnetcore-runtime image:

Error response from daemon: pull access denied for
microsoft/dotnet, repository does not exist or may
require 'docker login': denied: requested access to
the resource is denied

As mentioned before, the reason was: microsoft moved the out of support images from docker hub to microsoft container registry (MCR). To solve that problem, I updated the image to mcr.microsoft.com/dotnet/core/runtime:2.2. So, instead of pulling images from docker hub (microsoft/dotnet) you should pull them from MCR (mcr.microsoft.com), just like described below:

microsoft/dotnet:2.1-sdk -> mcr.microsoft.com/dotnet/sdk:2.1
microsoft/dotnet:2.1-aspnetcore-runtime -> mcr.microsoft.com/dotnet/aspnet:2.1
microsoft/dotnet:2.1-runtime -> mcr.microsoft.com/dotnet/runtime:2.1
microsoft/dotnet:2.1-runtime-deps -> mcr.microsoft.com/dotnet/runtime-deps:2.1

NOTE: see the full list of from docker hub to MCR images here

Maybe you're asking yourself: why microsoft announced that they removed the 2.1 images from docker hub but not the 2.2 images? The response is simple: .NET 2.2 was deprecated in December 23, 2019, so microsoft don't need to announce as they are not supporting it anymore 🤷‍♂️

NOTE: it's strongly recommended move to later .NET versions instead of using out of support versions like 2.1 or 2.2