Usage of PreqbaThemeXml and PreqbaThemeWxl in WiX v5 with custom bootstrapper

[yuvnith]

Question

In WiX v3, we used a custom bootstrapper application (BA) built on .NET Framework 4.8. To handle scenarios where .NET 4.8 was not installed on the target machine, we leveraged PreqbaThemeXml and PreqbaThemeWxl to override the default theme and display a custom UI when a prerequisite check (e.g., for .NET 4.8) failed.

However, in WiX v5, it appears that overriding the default themes in this way is no longer supported. Since our custom BA is built using .NET Framework 4.8, it cannot launch if the framework is missing, and we can no longer fall back to a custom theme to notify the user.

Question:
What is the recommended approach in WiX v5 to handle .NET Framework 4.8 prerequisites when the custom BA depends on it? Specifically:

• How can we detect .NET 4.8 before launching the managed BA?
• Is there a way to show a fallback UI or message if .NET 4.8 is not present?

Any guidance or examples would be greatly appreciated!

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