Visual Studio 2026 keeps generating .slnx instead of .sln even when Default Solution File Format is set to .sln (Unity compatibility issue)

Question

I am trying to configure Visual Studio 2026 Community (18.3.2) to generate traditional .sln solution files instead of the new .slnx format, because Unity Editor expects .sln files for project integration.

Environment

Visual Studio 2026 Community

Version: 18.3.2

Release: February 2026 Feature Update

Channel: Stable

Unity Editor: Unity 6.3 LTS (6000.3.10f1)

OS: Windows 11

What I tried

I changed the setting in:

Tools → Options → Projects and Solutions → General

Default Solution File Format:

.sln (Visual Studio 2010–2022 Solution File Format)

However, Visual Studio still generates .slnx files when opening or generating the solution for the Unity project.

Problem

Unity normally generates and works with .sln files, but Visual Studio 2026 keeps using .slnx even after changing the option above.

This causes issues with the expected Unity workflow where Unity regenerates and interacts with the .sln file.

Question

How can I force Visual Studio 2026 to use .sln instead of .slnx for solutions?

Is there:

another setting that overrides the solution format?

a registry setting or environment option controlling this?

a Unity compatibility workaround?

Additional Information

Screenshots show:

the Visual Studio version information

the solution format setting set to .sln

Unity Hub and installed Unity version

Despite the setting being changed, .slnx files continue to be created.

If someone has successfully configured Visual Studio 2026 to work with Unity using .sln instead of .slnx, I would appreciate guidance.

Answer

Thanks for reaching out. From the information shared, the behavior you are experiencing is expected when working with newer versions of Microsoft Visual Studio 2026 together with the Unity Editor.

Strating with newer Visual Studio releases, the IDE may generate .slnx solution files. However, when a project is managed by Unity, the solution and project files are generated and controlled by Unity itself, not by Visual Studio. Because of this, the Visual Studio setting under Tools-> Options-> Projects and Solutions-> General -> Default Solution File Format does not override Unity's generation process.

Why .slnx is still generated

When you open Unity Project in Visual Studio:

Unity regenerates the solution files whenever scripts are refreshed or the project is opened.
Unity determines the solution format it generates.
Visual Studio simply opens whatever solution Unity provides.

Therefore, even if Visual Studio is configured to prefer .sln, Unity may still recreate the solution using its own configuration.

Recommended Workaround

Please try the following steps to ensure Unity generates the traditional .sln files:

Open your project in Unity Hub.
In Unity Editor, navigate to: Edit -> Preferences -> External Tools.
Ender External Script Editor, select: Visual Studio
Enable the options:
1. Generate all .csproj files
2. Regenerate project files
Click Regenerate project files. After That:
Close Visual Studio.
Delete the following files from your Unity project root:
1. .slnx
2. .csproj
Reopen the project from Unity by double-clicking a script. Unity should regenerate the .sln solution file compatible with Visual Studio.

Additional Notes

if .slnx continues to be generated, it may indicate that the Unity version you are using has begun supporting the newer solution format. In that case, the behavior is controlled by Unity's integration package rather than Visual Studio.

You may also consider:

Updating the Visual Studio Tools for Unity component inside the Visual Studio Installer.
Updating Unity to the latest LTS patch where .sln compatibility improvements may be included.

Please let us know if you require any further assistance we’re happy to help. If you found this information useful, kindly mark this as "Accept Answer".

Share via