I was able to successfully install a previous version using the command:
Install-Package FluentAssertions.Mvc4 -Version 0.3.0
PM> Install-Package FluentAssertions.Mvc4
Attempting to resolve dependency 'FluentAssertions (≥ 2.2)'.
Attempting to resolve dependency 'Microsoft.AspNet.Mvc (≥ 4.0.30506.0)'.
Attempting to resolve dependency 'Microsoft.AspNet.WebPages (≥ 2.0.20710.0)'.
Attempting to resolve dependency 'Microsoft.Web.Infrastructure (≥ 1.0.0.0)'.
Attempting to resolve dependency 'Microsoft.AspNet.Razor (≥ 2.0.20710.0 && < 2.1)'.
Installing 'FluentAssertions.Mvc4 0.4.0.0'.
Successfully installed 'FluentAssertions.Mvc4 0.4.0.0'.
Adding 'FluentAssertions 2.2.0.0' to test.
Installing 'FluentAssertions 2.2.0.0'.
You are downloading FluentAssertions from Dennis Doomen, Martin Opdam, the license agreement to which is available at https://github.com/dennisdoomen/FluentAssertions/blob/master/LICENSE. Check the package for additional dependencies, which may come with their own license agreement(s). Your use of the package and dependencies constitutes your acceptance of their license agreements. If you do not accept the license agreement(s), then delete the relevant components from your device.
Successfully installed 'FluentAssertions 2.2.0.0'.
Successfully added 'FluentAssertions 2.2.0.0' to test.
Adding 'Microsoft.Web.Infrastructure 1.0.0.0' to test.
Successfully added 'Microsoft.Web.Infrastructure 1.0.0.0' to test.
Adding 'Microsoft.AspNet.Razor 2.0.20710.0' to test.
Successfully added 'Microsoft.AspNet.Razor 2.0.20710.0' to test.
Adding 'Microsoft.AspNet.WebPages 2.0.20710.0' to test.
Successfully added 'Microsoft.AspNet.WebPages 2.0.20710.0' to test.
Adding 'Microsoft.AspNet.Mvc 4.0.30506.0' to test.
Successfully added 'Microsoft.AspNet.Mvc 4.0.30506.0' to test.
Adding 'FluentAssertions.Mvc4 0.4.0.0' to test.
Uninstalling 'FluentAssertions.Mvc4 0.4.0.0'.
Successfully uninstalled 'FluentAssertions.Mvc4 0.4.0.0'.
Uninstalling 'FluentAssertions 2.2.0.0'.
Successfully uninstalled 'FluentAssertions 2.2.0.0'.
Install failed. Rolling back...
Install-Package : Could not install package 'FluentAssertions.Mvc4 0.4.0.0'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.0', but
the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.
At line:1 char:16
+ Install-Package <<<< FluentAssertions.Mvc4
+ CategoryInfo : NotSpecified: (:) [Install-Package], InvalidOperationException
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
There was an issue with an earlier version of the FA core which needed .net 4.0.3. They have resolved that issue now so I'll push an update to NuGet in the next day or two.
Please see the Package Manager error below.
I was able to successfully install a previous version using the command: Install-Package FluentAssertions.Mvc4 -Version 0.3.0