Xcode 26.4 - Old skip project - Missing preview error

[macshodan]

Since I've updated to the latest Xcode (26.4) I'm not able to render SwiftUI Previews in Xcode. Every view I try to render have this very same error:

Missing Preview
Ensure preview is compiled for active scheme & destination
If the preview is excluded from the build it will be missing in the Xcode canvas. The file containing the preview must be compiled by the active scheme for your given destination. Check if the preview is filtered out by compile-time checks, dead code stripping, or other settings.

I've tried several projects created in the past few months, all of them have this issue. If I open the very same project on Xcode 26.3 previews works fine.

I've tried to create a new project with skip create, added the #Preview macro to the ContentView and it works. I then tried to compare the build settings on both projects and I didn't see any difference. Even tried to launch skip verify --fix on the old projects, but no luck.

Anybody else have this issue? Or any hint on where to look to try and fix it?

ps: here's the diagnostic report from the preview:

Diagnostic report.txt

[marcprux]

Skip has had issues with Previews in the past (see #72), but we've historically been about to work around the issues with the Canvas / Use Legacy Previews Execution option (which unfortunately gets reset every time Xcode has an upgrade). Can you try enabling that and seeing if it helps?

[macshodan]

Hi, thanks for your reply. Unfortunately it was one of the first things I've tried, but when I enable Legacy Preview Execution I got another error: Failed to build <View>.swift with the info Compiling failed: cannot find type 'View' in scope.

When I disable the legacy preview I only got this error (which I suspect it's very similar but only with less info):

[macshodan]

Hello! A little update to the issue.

I managed to get the previews working by creating a new skip project and manually copying all the files from the old one. Now the previews works without the legacy execution.

I've tried to look at all the config files, build options, etc... but I can't see any difference between the 2 projects... it really puzzled me