Hi, I am developing the Click & Read web add-on for Chromium, Firefox and Safari. We use xcrun safari-web-extension-converter tool to generate the Safari add-on. The build on Xcode had no meaning errors/warnings, until we had to switch to a more up-to-date MacBook (required as deprecated Mac had no support for latest macOS and thus for Xcode compatibility !). So now I build my add-on on an Apple M1 MB Air on Sequoia 15.0 with latest Xcode, but I encounter an error ? or warning ? : NSBundle file:///System/Library/PrivateFrameworks/MetalTools.framework/ principal class is nil because all fallbacks have failed Unable to create bundle at URL ((null)): normalized URL null Unable to create bundle at URL ((null)): normalized URL null Unable to create bundle at URL ((null)): normalized URL null But it doesn't prevent the add-on build to complete as I am able to open it onto Safari. Then, when loading the add-on on a test web page, I get this error on safari console: Error: Invalid call to runtime.connect(). No runtime.onConnect listeners found. BTW, the same add-on Dist works as expected on Chrome or Firefox (on macOS). So it seems the runtime listener runtime.onConnect.addListener isn't initiated on Background script... Thanks for your feedback and help