This has nothing to do with Mac OS X Sierra (v10.12). This is a problem with the download. I just updated on Yosemite, and the same problem occurs. @lubos, you have a problem with the Mac OS X download.
I also tested the reboot solution from the lengthy discussion on the Mono framework. That did not solve the problem.
From what people have said, things worked at 16.9.71, still worked at 16.9.72, but went haywire on some version after that.