Using 18.6 worked for me.

Happening on 18.4 for me as well.

NO apparently SIP prevents it: Mac-Studio:Volumes MGW$ sudo cp -f "/Library/Developer/CoreSimulator/Volumes/iOS_22G86/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.6.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib" "/Library/Developer/CoreSimulator/Volumes/iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/" cp: /Library/Developer/CoreSimulator/Volumes/iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib: Operation not permitted

Can I temporarily copy it into place from one of the other locations? Mac-Studio:Volumes MGW$ cd /Library/Developer/CoreSimulator/Volumes Mac-Studio:Volumes MGW$ ls iOS_21A342 iOS_21E213 iOS_22A3351 iOS_22C150 iOS_22G86 iOS_21C62 iOS_21F79 iOS_22B81 iOS_22E238 tvOS_22L572 Mac-Studio:Volumes MGW$ find . -name libswiftWebKit.dylib -print ./iOS_21A342/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.0.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib ./iOS_22C150/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib find: ./iOS_22C150/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.2.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied ./iOS_21C62/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.2.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib ./iOS_22G86/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.6.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib ./iOS_22G86/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.6.simruntime/Contents/Resources/RuntimeRoot/System/Cryptexes/OS/usr/lib/swift/libswiftWebKit.dylib find: ./iOS_22G86/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.6.simruntime/Contents/Resources/RuntimeRoot/private/var/mobile: Permission denied find: ./iOS_22G86/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.6.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied ./iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/System/Cryptexes/OS/usr/lib/swift/libswiftWebKit.dylib find: ./iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/private/var/mobile: Permission denied find: ./iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied ./iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib ./iOS_21F79/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.5.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib ./tvOS_22L572/Library/Developer/CoreSimulator/Profiles/Runtimes/tvOS 18.5.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib find: ./tvOS_22L572/Library/Developer/CoreSimulator/Profiles/Runtimes/tvOS 18.5.simruntime/Contents/Resources/RuntimeRoot/private/var/mobile: Permission denied find: ./tvOS_22L572/Library/Developer/CoreSimulator/Profiles/Runtimes/tvOS 18.5.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied ./iOS_22B81/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.1.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib find: ./iOS_22B81/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.1.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied ./iOS_22A3351/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.0.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib find: ./iOS_22A3351/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.0.simruntime/Contents/Resources/RuntimeRoot/private/var/db/modelmanagerd: Permission denied

I have the same issue, and do not have the library there: Mac-Studio:Volumes MGW$ ls /usr/lib/swift libswiftCreateML.dylib libswiftShazamKit.dylib libswiftVirtualization.dylib libswiftIdentityLookup.dylib libswiftSoundAnalysis_Private.dylib playgrounds libswiftRemoteMirror.dylib libswiftSoundAnalysis.dylib How do install the library? Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: DYLD 1 Library missing Library not loaded: /usr/lib/swift/libswiftWebKit.dylib Referenced from: <0A128AB5-ED39-36A9-8EC3-7231029D42D3> /Users/USER/Library/Developer/CoreSimulator/Devices/CA0B3CCD-BD38-4766-A17E-463632FFDD04/data/Containers/Bundle/Application/915B71DC-BD1F-412F-A5EA-62C2867FAEF1/Runner.app/Frameworks/flutter_inappwebview_ios.framework/flutter_inappwebview_ios Reason: tried: '/Library/Developer/CoreSimulator/Volumes/iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftWebKit.dylib' (no such file), '/usr/lib/swift/libswiftWebKit.dylib' (no such file, not in dyld cache), '/Library/Developer/CoreSimulator/Volumes/iOS_22E238/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/libswiftWebKit.dylib' (no such file) (terminated at launch; ignore backtrace)