I have managed to crash Qbs several times in the past, every time due to a cyclic reference occurring. This time I decided to build a debug version of Qbs and capture the bug myself to see what is going on. Long story short, I narrowed it down to this:

Product{
    name: "Test Product"
    Group{
        prefix:prefix

         }
}

Just put this in a .qbs file and let qbs read it. You could say why do I end up with this stupid syntax? The reason is that I want to do the following:

import qbs.FileInfo

Product {
    name: "Test Product"
    property string prefix: FileInfo.joinPaths(FileInfo.cleanPath(project.sourceDirectory), "somedir")
    MyGroup {
        name: "Test Group"
        prefix: prefix // <---  This is where the bug is triggered

          }
}

As you can see here there is a prefix property I want to pass from Product to MyGroup. In other words it is a legitimate mistake that can happen in normal use.

I sure hope this can be fixed and a regression test is added to the test suite so that it won't happen in the future!