Upgrade Visual Studio 2013 solutions to Visual Studio 2015

Note: This works for VS 2015 and 2017

An alternative to hand-editing the .sln file or re-saving on top of the original .sln file:

1. Open the solution in Visual Studio
2. Right click solution > Add > New Solution Folder (name does not matter)
3. Save solution
4. Delete the newly added solution folder
5. Save solution

The solution will now be upgraded.

Change the version in the .sln file

# Visual Studio 2013
VisualStudioVersion = 12.0.31101.0

To match whatever version you have

As of this morning my VS Enterprise is 14.0.23107.0

Example:

# Visual Studio 2015
VisualStudioVersion = 14.0.23107.0

---

Visual Studio 2015 Update 3 is 14.0.25420.1

The simplest solution IMO (also worked for 2012 and 2013) is:

1. Open the solution file using Visual Studio 2015
2. Select the solution file in Solution Explorer
3. Select File / Save MySolution.sln As...
4. Overwrite the existing solution file.

I ran across this looking for the same thing. The accepted answer works, but I noticed some comments about not being batchable. I found an option for batching and I thought I'd share.

You can use the /upgrade option in devenv.com. This means it's batchable. For example, to recurse the current directory upgrading all .sln files (after backing them up), you could do this:

dir -Recurse -path ".\" *.sln | ForEach-object {
    Copy-Item $_.FullName "$($_.DirectoryName)\$($_.Name.Remove($_.Name.Length - $_.Extension.Length)).vs2013$($_.Extension)";
    & "C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\devenv.com" /upgrade $_.FullName
}