Umbraco-CMS: Umbraco V7.5.11 upgrade doesn't actually work

Which Umbraco version are you using? (Please write the exact version, example: 10.1.0)

7.15.11

Bug summary

I have a client with EOL V7 support, and it states that they have to be on the latest version of V7 for the support to be valid. They are currently on 7.15.10 and we noticed that 7.15.11 was released recently. However, attempting to upgrade from v7.15.10 to v7.5.11 in visual studio via nuget fails with the error:

Unable to find a version of 'Microsoft.CodeDom.Providers.DotNetCompilerPlatform' that is compatible with 'UmbracoCms 7.15.11 constraint: Microsoft.CodeDom.Providers.DotNetCompilerPlatform (>= 2.0.1 && < 3.0.0)'.

Specifics

We have tried this with four V7 websites, all at various versions, and none of them are able to apply the latest update via nuget in Visual Studio. We’ve also had various developers in various locations reproduce the same issue.

To confirm this was an issue with the package, we set up a brand new V7.5.10 website and attempted to apply the 7.5.11 update and got the same error, so it’s definitely the update and not anything in our code.

Oddly, despite the error saying it can’t find a compatible version, version 2.0.1 of the compiler is already installed on the site as a package from the original Umbraco install, and there are no other packages that come between 2.0.1 and 3 on nuget.

Steps to reproduce

To replicate with a fresh install, do the following:

• Create an new web application project in VS2022
• Install Umbraco 7.15.10 via nuget
• Run the site and setup a local copy of umbraco
• In the nuget package manager in VS2022 attempt to upgrade the site to 7.15.11
• You will see the error in the package manager output window after it has attempted to gather the dependencies

UPDATE: I think the nuget package is fundamentally broken, if you try and do a fresh install of 7.15.11 you get the following error:

Unable to find a version of 'LightInject' that is compatible with 'UmbracoCms.Core 8.5.0 constraint: LightInject (>= 5.4.0 && < 5.999999.0)'.

Which we shouldn’t get, because the package is targeting 7.X not 8.

Expected result / actual result

Running the nuget upgrade should update the site to 7.15.11 successfully.