Hi
I have always been able to upgrade to the latest version, but the 64bit version for upgrading to 15.4.2 from 15.4.1 just fails with the message as shown below. Operating system is Windows 10 Home.
It looks like temporary windows folder is full, corrupt or not accessible.
To clean the temporary windows folder, you can use "disk cleanup"
To solve issues with permissions please check the configuration of your firewall or virusscanner.
I did run disk cleanup before writing. However, looking again I noted that I needed to be in as Admin! Sorry for the inconvenience and all ok now I've done it correctly. Doh!!!!