I finally got v1.12 to install.
Looking carefully at the installer log suggested that it was having a problem because there was a space in the name of the folder containing the installer. I tested this by moving the installer package to the desktop, and it worked fine. Then I simply removed the space from the name of the folder to which the package had been downloaded and tried the installer from there, and it worked fine. If I put the space back in the folder name the installer failed.