Retargeting All Projects in a Solution to .NET 4.5.2
I have a solution in Visual Studio 2012 with 170 C# projects in it. I need to retarget all of the projects from .NET Framework 4.0 to 4.5.2.
I prefer to let Visual Studio handle this by going into the properties of each project, changing the targeted framework, and letting Visual Studio make any necessary changes to the .csproj files.
I noticed that these changes include adding a few new XML tags to the .csproj, depending on some attributes of the current project.
How can I batch retarget all 170 C# projects without just using a replace text tool to replace the targeted version number? I want Visual Studio to make all the necessary tag modifications and additions and replace alone will not permit that to happen.
Answer
The MSDN documentation "Migration Guide to the .NET Framework 4.5" and "How to Configure an App to Support .NET Framework 4 or 4.5" only discusses modifying projects. There's no details on applying changes to the entire solution at once, nor have I seen a function in VS that supports it.
However, there's a (well-rated) extension called Target Framework Migrator available in the Visual Studio gallery, which supports upgrading to 4.5.2 (as well as newer versions**) and looks like it'll do exactly what you want. The source code is available on GitHub, if you're interested.
Note that the lack of such a feature may be intentional (and not just an omission). I'm just guessing, but maybe MS figures only projects that need the new Frameworks will be upgraded. FWIW, if you end up upgrading some projects that are shared with other solutions, those solutions may fail to build until they're upgraded too.
That being said, if you're in a small shop with just one (or a few) solutions and you're looking to upgrade everything in one go, then perhaps the above tool will work for you.
There's been no development on this for years, and apparently the developer has no plans to pass the baton to anyone else.
If you're unable to get it to work with a newer .NET Framework version, check the existing PRs and Issues for fixes, but you may have to apply them yourself. For example, someone posted a fix for .NET Framework v 4.7.1. Hopefully these will get merged, but I wouldn't hold my breath.
If anyone else is seeing the same error as Anas (in the comments), here's a GitHub issue from a couple weeks ago, and another possibly related issue from 2017. Consider thumbs upping them and adding more details if you're having the same problem.