Can't submit apps to AppStore: ERROR ITMS-90534: "Invalid Toolchain

Question

ERROR ITMS-90534: \"Invalid Toolchain.

New apps and app updates must be built with the public (GM) versions of Xcode 6 or later, macOS,

Answer 1

I just want to add what is says at the bottom of the Using Apple Beta Software page (https://developer.apple.com/support/beta-software/) IF you are using a BETA version of XCode and try to submit it will fail every time UNLESS you are on a GM_seed (Golden Master release, aka the release before the release to production) Since I do not have enough "reputation" to comment @Chuck Smith. I created this. Hope this helps. Today is 11/8/2019 and I downloaded and submitted my app with success.

Submitting Apps

Apps that are created using beta versions of Xcode or that are built for beta versions of an OS will not be accepted on the App Store. Apps that you submit should be developed using the most up-to-date version of Xcode from the Mac App Store and should be built for publicly available versions of iOS, macOS, watchOS, and tvOS — except when GM seeds are available. When a GM Seed of Xcode becomes available, use it to develop your app for submission. When GM seeds of iOS, macOS, watchOS, or tvOS become available, build your app for these versions.