The feature 'global using directive' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version

 The error message you're seeing indicates that the "global using directive" feature is currently unsupported in the version of C# you're using. To resolve this issue, you can follow these steps:

Step 1: Open the `.csproj` file of your project.

Step 2: Locate the `<LangVersion>` element within the `<PropertyGroup>` section.

Step 3: Modify the `<LangVersion>` element to include the "preview" language version. It should look like this:

<PropertyGroup>

  <LangVersion>preview</LangVersion>

</PropertyGroup>

Step 4: Save the changes to the `.csproj` file.

Step 5: Rebuild your project.

By setting the language version to "preview," you enable the use of preview features, including the "global using directive." However, please note that preview features are subject to change and may not be suitable for production environments. It's important to exercise caution when using preview features and to consider upgrading to a stable release once available.

After applying these changes, rebuild your project and verify if the error is resolved.