msbuild 17.13 fails to build "version 13" solutions

[znakeeye]

Just upgraded to VS 17.13. Now msbuild fails to build my solutions. E.g. msbuild test.sln gives me this error:

C:\git\test.sln : error MSB4025: The project file could not be loade
d. System.AggregateException: One or more errors occurred. ---> Microsoft.VisualStudio.SolutionPersistence.Model.Soluti
onException: The file version '13' is unsupported.

Steps to reproduce

1. Create an empty C++ project/solution.
2. Change the version of the .sln file to 13.00. Not sure where I got this number from, but it's been in our repo for many years.

Microsoft Visual Studio Solution File, Format Version 13.00

If you search Github for that string, you'll find some 1200 references. What's up with this?

[CyrusNajmabadi]

This is not the MSBuild repo.

[surayya-MS]

This is not a bug. The latest supported version is 12.00. Format Version 13.00 doesn't exist. Please change it to 12.00.

Previously this worked because MSBuild solution parser didn't check the format version. Now, we use Microsoft.VisualStudio.SolutionPersistence to parse solution. The change was introduced in #10836

Here is the test ensuring this https://github.com/microsoft/vs-solutionpersistence/blob/0b6f82a4073ce0ff0419991ea0cd6dd6898a51ac/test/Microsoft.VisualStudio.SolutionPersistence.Tests/Serialization/InvalidSolutions.cs#L190