fun useful while it lasted—after suggesting some alternative iPhone management apps, it turns out that updating to iOS 8.3 will disable some of the functionality of those apps. According to MacRumors, this affects virtually any “file manager” except for iTunes. From the developers of iFunBox:
Apple blocked access of the entire sandbox directory of every installed App since iOS 8.3…Before there is a solution, iFunBox will fail to open data directory of any App if the device is not jailbroken.
iFunBox also reported over the weekend they have found a partial work around for those interested. Sandbox access will work with apps that have the "UIFileSharingEnabled" key set to true in their info.plist but access is limited to the /Documents directory.
Hopefully this is an inadvertent side effect of the iOS update. Right now iExplorer and and iFunBox are at least functional, with updates required from other developers to get things going as they should be.
Right now if it’s that important to you there’s still a possibility of downgrading, or you could hold off on the 8.3 update if you haven’t run it already.