Sorry that you're seeing this problem with 12.14.
Please try everything here:
If you have already looked there, please see the last few suggestions, as I've just added some additional ones based on threads from a few months ago where people had similar problems. (These usually turned out not to be due to the installer, but due to something else on the system not liking the installer being something new, e.g. antivirus killing an unrecognised process.)