When attempting to run a build on a connected iOS device in Xcode I get the error:

  
Could not find Developer Disk Image

I saw that there was a public beta for Xcode, so I installed it.

One of the new features is that you don't need to have a Developer Program Account Dingus to upload your app directly to your iPhone.

However, on my iPhone 4s, I also did a public beta update to iOS 8.4, problem being, that there's no Developer Disk Image available for it.

Where do I to find it or how can it be fixed?