Question: An app extension is causing a code signing issue. This app is already on the Appstore (with this extension) yet overnight for some reason when I have come back to this app im getting![enter image description here](https://i.stack.imgur.com/jsrhn.png)

A strange error as its contradicting itself by showing two exact identical certificates in said error message.

Ive tried 
clean and restart, deleting derived data, regenerating provisioning profiles, deleting and creating new profiles. using both xcode 6.1 and xcode beta and [This](http://aplus.rs/2014/embedded-binary-is-not-signed-with-the-same-certificate-as-the-parent-app/)

I have also searched SO [Xcode6:Embedded binary is not signed with the same certificate as the parent app](https://stackoverflow.com/questions/25927604/xcode6embedded-binary-is-not-signed-with-the-same-certificate-as-the-parent-app) and no solutions offered worked

(Deleting the app extension removes the error)

Answer: 
My problem was that I had a Copy Files post-build step that was causing the issue (somehow).

Once I removed that Copy Files phase, this error went away..
What fixed this for me was:

1. Re-Logging to my accounts in Preferences -> Accounts.
2. Turning App Groups OFF in both (main app + keyboard extension) Targets (under Target -> Capabilities), then turning them back ON and re-selecting/re-checking the app groups.