VS 2026: Project "incompatible", "application is not installed"

[chrullrich]

(It looks like I solved my problem while writing it down, so perhaps this can be of use to someone else.)

I have two installations of VS 2026 (18.0.2) on two different PCs. Both have HeatWave 1.0.6 (1.0.6.7 according to the VS's About box) installed.

On the first PC an existing installer project that worked fine in VS 2022 initially showed up as "incompatible". I reinstalled HeatWave to no effect. Eventually I deleted the project and recreated it (using the same WiX file); the .wixproj came out much shorter. Since then that VS installation is fine with the project.

After transporting the entire solution to the other PC (by means of Git), the installer project is again "incompatible" there. Removing and re-adding the project will apparently make it compatible, but that just means the change to the solution file will keep bouncing around between computers forever.

I found that deleting the .vs directory in the solution root will fix this. Somewhere deep down in there the project GUID from the solution file appears (in something called solution.vc.db), and because the .vs directory is not in version control the inconsistency breaks whatever it is in HeatWave or VS that matches the project to the extension.

[lauraposner]

My teammate and I had the same issue for WiX project files upgraded from WiX v3.x. When we removed and readded the WiX project to the solution in VS2026, we noticed that the project type GUID in the solution file was changing from "930C7802-8A8C-48F9-8165-68863BCCD9DD" (which from Googling appears to be associated with WiX projects) to "B7DD6F7E-DEF8-4E67-B5B7-07EF123DB6F0", which is the same project type GUID that gets added if we use the HeatWave for VS2022 extension to add a new WiX MSI package project to the same solution. Updating the project type GUID for the WiX project in the solution file alone, we can now load the WiX project in VS2026.

[mc0re]

Same. HeatWave didn't modify project type GUID in the .sln file during the upgrade. I spent over a day hunting the errors in vain before I decided to check the project type GUID :-D