My current project in Swift 3.2 and Xcode 8.3 this error comes today even I have successfully uploaded to iTunes before 3 days.
ERROR ITMS-90725: "SDK Version Issue. This app was built with the iOS '10.3' SDK. All new iOS apps submitted to the App Store must be built with the iOS '11.0' SDK or later, included in Xcode [9.0] or later. Please update Xcode and rebuild your app."
I met with similar problem now and found solution for it. My warning looked like following:
App was built and uploaded with the newest stable XCode (10.1)
To check what SDK indeed you have installed, use terminal with following command:
In response you will get printed all SDKs. In my case the problem was double SDK 12.1, but one of them was pointing on wrong path (like for iPhoneOS12.0.sdk):
Solution
Solution in this case is simple.
There you will find 2 shortcuts pointing to iPhoneOS.sdk.
Remove iPhoneOS12.0.sdk alias.
Well done.
Probably XCode takes wrong SDK based on aliases available in SDKs folder. In my case solution provided above made it working correctly without any warning.
From Apple's Submitting apps to the App Store:
And a related (older but probably useful) Technical Note: