Xcode 6: iOS 8.1 The Developer Disk Image could not be mounted

Solution 1:

Xcode 6 only contains the iOS 8.0 SDK.

If you're running iOS 8.1 on your phone, then you'll need to upgrade to Xcode 6.1, which contains the iOS 8.1 SDK.

Solution 2:

Download the latest version of Xcode from the App Store. I had an early version of XCode 6.1 that lacked the 8.1 SDK. Upgrading to the latest fixed the problem.

Solution 3:

Restarting my phone cleared this for me.

It started a day after updating to Xcode 6.1 and phone (4s) to 8.1 worked fine to start with then stopped with this message a day later.

Solution 4:

Opening project in Xcode 6.1 then again in 6.0.1 seemed to fix issue, if your project is not ready to be compiled in 6.1!

Solution 5:

Did you check your apps' base version. If the base version is set to 8 and your device is 7, you will probably get this error.

and if your base version, from what i imagine is 8.1 and your device is not updated to 8.1 it wont work either.