Hello @thomas magami , Azure.Storage.Blobs latest version (12.18.0) supports .NET Framework 4.6.2 which is the minimum version supported by modern versions of Visual Studio. You should upgrade both your .NET Framework and Visual Studio version to, at least, versions 4.6.2 and 2017 respectively.
For information take a look to Visual Studio Product Lifecycle and Servicing and Microsoft .NET Framework.
Let us know if you need additional assistance. If the answer was helpful, please accept it and rate it so that others facing a similar issue can easily find a solution.