After upgrading to OSX High Sierra, some Mac users may encounter a problem with Time Machine backing up to external device, including Apollo Cloud, and pop up an error message "Time Machine can't connect to the backup disk. The operation couldn't be completed. (OSStatus error 17.)"

To solve this problem,

  1. Go Time Machine Preference to remove Apollo Disk and select it again.  When the authentication prompt comes up, DO NOT enter anything but keep the authentication prompt open;
  2. Go Apollo icon on the top menu bar.  Select Folder Mount Status and turn off Apollo Time Machine to make it unmounted, or eject from Finder shared Apollo Time Machine;
  3. Sign in to the waiting prompt;
  4. Turn on Time Machine Status on Apollo.

Now the Apollo Time Machine disk should be added and connected.