A suitable version of 7zip was not found...

[tksharpless]

The full story...

A suitable version of 7zip was not found (required v24.9.0) Downloading portable 7zip 24.9.0...
Extracting 7zip...
CMake Error: Problem with archive_read_next_header():
CMake Error: Problem extracting tar: D:\opensource\vcpkg\downloads\7z2409.7z
'CMake' failed while extracting D:\opensource\vcpkg\downloads\7z2409.7z.

So vcpkg can't install 7-zip for its own use.
Of course I have a working installation of 7-zip. How can I make vcpkg use it?

[tksharpless]

The problem is evidently in the cmake extraction process -- WinRAR was able to extract the archive to the tool directory, after which vcpkg was able to install 7zip.