When I went to update my Calibre desktop client (64-bit on Windows 8.1, x64), the
download page indicated that I would be downloading version 2.11 (as you can see on
this screenshot) - which was a little weird to me, because I remember being on a higher version, but whatever, maybe the way you guys do versioning is different from what I am used to. So I downloaded 2.11, but when I ran the installer it complained that the file
calibre-64bit-2.9.0.msi could not be found in my Downloads folder - which makes sense, I had
calibre-64bit-2.11.0.msi in there. Renaming the file seemed to have worked fine (I can launch the Calibre client and it doesn't prompt me to update), but I wanted to bring this to your attention.