Apple Watch - Another launch session is already waiting to debug the app extension with identifier

Question

I was debugging my Apple Watch extension with my app, and I've suddenly started to get Another launch session is already waiting to debug the app extension with identifier : my watch extension id error. I've restarted Xcode, my phone, and my watch, then tried again, but I'm still getting the same error. After restarting all, I've selected my Watch target to run on my phone + watch, hit Run once, and waited. I'm on iOS 9.2 and watchOS 2.1.

How can I get rid of this error?

Answer 1

Try going to the stop button (top-left of Xcode) and make sure there isn't a dropdown icon at the bottom-right of the stop button. If there is, click it, and then click each application listed to stop all applications. Then, rebuild your application.

Answer 2

Restarting my Mac fixed the issue.