[sandysot]

After much research and anguish I have determined that the Calibre features add books/convert books can no longer work within the new win 10 or OS El Capitan operating systems.I have Calibre & Calibre2 installed in one of each type computer and they are unable to function as before in win7/8. My experience with apple is limited to a new Mac pro which came with El Capitan OS, in which I am greatly disappointed. Both these OS's have reformatted my old book files into proprietary types not responsive to Calibre, have introduced new book control agents (like Apple System Book Agent) and relocated them to inaccessible places not reachable by Calibre.Further, Apple has erased the Calibre accessible iTunes program and instituted a captive program named iBooks that responds only to Apple books.Library books for kindle are likewise not available to Calibre and therefor incapacitated unless there is a workaround that I have not yet found.Others have made efforts to uninstall iBooks and reinstall the old iTunes to no avail.These changes are deep in the OS architecture and unrepairable, so if i could, I'd go back to win 7 or 8.Or at least don't upgrade to ElCapitan.All comment and criticism of this post will be welcomed.I would be glad to learn of any answers that can revive my old Calibre usefulness.