(What’s this obsession with posting the most minimal part of a log possible, hiding all that could be relevant).
It seems the compiler is either not getting a source file or a reference that defines buildIT. Can I assume from the title that tis should come from a referenced dll or project? Is it a project reference or a .dll reference? Is other project being built with EBuild, or with the .Legacy.targets file? What build is this, 2313?
All important questions, most of which I could answer myself if, having the compete log instead of a cropped-to-death screenshot.
Note that EBuild will fail on failed references. So if this is EBuild, the reference is not unresolved, its not there (for whatever reasons). If this is Legacy.targets, i.e. MSBuild, it might have just failed to resolve quietly — why knows, MSBuild doesn’t tell us. One of the reasons why EBuild is stricter there.
Note also that if one of the projects uses EBuild and the other does not, you could be running in the same (open) issue we already discussed, where project references between MSBuild and EBuild don’t resolve properly (“80347: VS/EBuild: MSBuild project cannot see project reference to EBuild project”). That’s still open, so if that’s the scenario, it’s expected that that isn’t fixed yet. Go all-or-nothing EBuild or Legacy, to work around that.