The .slnx format is Microsoft's XML-based replacement for the legacy .sln solution file. It eliminates GUIDs, removes cross-multiplied configuration tables, and produces far fewer lines of markup — making it human-readable and less prone to merge conflicts. Supported since .NET 9.0.200 and Visual Studio 17.13+, it becomes the default with dotnet new sln in .NET 10. Migration is a single command (dotnet sln migrate), but requires checking SDK version compatibility, updating CI pipeline glob patterns, and auditing third-party tooling like slngen that may not yet support the new format. For new projects, adopting .slnx immediately is recommended; for existing codebases, a planned migration with a tooling audit is advised.
Table of contents
A Quick SLN RetrospectiveLooking Inside the .slnxMigrating Existing ProjectsSome Rough EdgesWrapping UpFurther Reading10.7K Impressions