Sample project to show this error WebKit internal crash/bug occurs when on (Intel Mac/Xcode14 beta5/Simulator/iOS16) and running WKWebView.evaluateJavaScript(..) {} . The closure passed does not get called and a WebKit crash is logged in console. This happens only when all the cases are met: Developer on Intel Mac Xcode 14 beta5 Simulator on iOS 16 There is no issue when tested on a lower verison from the above cases, i.e. tested on iOS 15.5. The eror logs that show a WebKit crash: [ProcessSuspension] endowmentsForHandle: Process with PID 62886 is not running 2022-08-24 07:24:08.094225+1000 xctest[62886:2912224] [Process] 0x114064100 - [PID=0] WebProcessProxy::didFinishLaunching: Invalid connection identifier (web process failed to launch) 2022-08-24 07:24:08.094369+1000 xctest[62886:2912224] [Process] 0x114064100 - [PID=0] WebProcessProxy::processDidTerminateOrFailedToLaunch: reason=Crash 2022-08-24 07:24:08.094656+1000 xctest[62886:2912224] [Process] 0x7fcb96020c20 - [pageProxyID=6, webPageID=7, PID=0] WebPageProxy::processDidTerminate: (pid 0), reason=Crash 2022-08-24 07:24:08.095603+1000 xctest[62886:2912224] [Loading] 0x7fcb96020c20 - [pageProxyID=6, webPageID=7, PID=0] WebPageProxy::dispatchProcessDidTerminate: reason=Crash 2022-08-24 07:24:08.095762+1000 xctest[62886:2912224] [Loading] 0x7fcb96020c20 - [pageProxyID=6, webPageID=7, PID=0] Sometimes this is accompanied by a crash related to PosterBoard.app similar to what is mentioned in the forum here