I have had this issue for years now, since v11 that I can remember... Each time I get a minor update to Parallels or when going from v11 to v12 or v12 to v13, this problem happens. During the v11 or v12 days, before I figured this out, I started ignoring or skipping the incremental updates as I didn't know how to fix it. Now though, I've gotten so used to it, I let it run through the steps, let it fail, restart Windows*, and then go the the %TEMP% folder and run the 'setup' from the PrlToolsPackage folder. That works each time (so far!). Why is this necessary ? * If you don't restart Windows before trying the manual install, it always fails to install with a file copying error (that I don't recall).