I downloaded and attempted to install 2.9 over 2.8.5.  The installer "uninstalled" previous version and then began to install 2.9.  While copying various and numerous dlls and possibly other files, error occurred - 

unable to open file for write.  In all cases, the files had been left behind, and the proper versions were there.  Using the ignore option on the error popup, I was able to complete the install.  Picard appears to be working correctly.

I did not check the box for removing settings during the uninstall.