With HeatWave, you can convert WiX v3 .wixproj projects to WiX v4 using the
Upgrade to WiX v4 command on the Project menu or context menu in Solution Explorer.
When you confirm, HeatWave converts the WiX v3 .wixproj to v4 as an SDK-style MSBuild project. It also converts the WiX source files you selected. If HeatWave encountered any errors during the automated conversion, it shows them in a .log file so you can rectify the problem using human-brain-style conversion. The WiX team is collecting real-world reports of how to handle manual conversion here.