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: 
So if anyone comes across this cryptic message the "App Group" switch in Capabilities of the app extension was off for some reason. Turned it back on and all good. Fix any "issues" if it requires you to when you do this
When I had this issue I went to the Apple Member Center and realized that the Provisioning Profile (for the extension) that I had created was marked as 'Invalid'. I just re-created the Provisioning Profile with the same certificate that the app is signed with and then downloaded it via Xcode > Preferences > Account > refresh. 

Once I had the new provisioning profiles I selected them in the build settings. I selected the provisioning profile that was just created and also selected the corresponding certificate in the Code signing entity in the build settings and that fixed the issue. 

Note that the extension has its own app id and hence its own provisioning profile.