We've ran into this issue on iOS 17 Simulator, too. Getting SetProperty: RPC timeout. Apparently deadlocked. Aborting now. with stacktraces looking like this: 0x125b1f124 - /usr/lib/system/libsystem_pthread.dylib : pthread_kill 2024-07-26 10:32:22.997235+0200 VoizeSDKDemo[19261:2764555] [default] SetProperty: RPC timeout. Apparently deadlocked. Aborting now. 0x123eef5c0 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/usr/lib/system/libsystem_c.dylib : abort 0x12c656400 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore : _Z14_CheckRPCErrorPKcii 0x12c65656c - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore : _Z14_CheckRPCErrorPKcii 0x358dc0d0c - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib : _ZN10AURemoteIO11SetPropertyEjjjPKvj 0x358dbfb40 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib : _ZN10AURemoteIO10InitializeEv 0x358e0a614 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib : _ZN5ausdk6AUBase12DoInitializeEv 0x358e0bfe8 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib : _ZN5ausdkL18AUMethodInitializeEPv 0x12c800dd4 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore : AudioUnitInitialize 0x12c770b04 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore : -[AUAudioUnitV2Bridge allocateRenderResourcesAndReturnError:] 0x13cd74424 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AVFAudio.framework/AVFAudio : _ZN17AUInterfaceBaseV310InitializeEv 0x13cd5c8ac - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AVFAudio.framework/AVFAudio : _ZN17AVAudioIONodeImpl14GetInputFormatEm 0x13cd55cb8 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AVFAudio.framework/AVFAudio : -[AVAudioNode inputFormatForBus:] 0x13cd6ec98 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AVFAudio.framework/AVFAudio : _ZN17AVAudioEngineImpl15UpdateInputNodeEb 0x13cd6b0e8 - /Library/Developer/CoreSimulator/Volumes/iOS_21E213/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 17.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AVFAudio.framework/AVFAudio : -[AVAudioEngine inputNode] We were calling audioEngine.inputNode.inputFormatForBus(bus) and audioEngine.inputNode.outputFormatForBus repeatedly on separate threads for debugging purposes. It looks like calling the inputNode getter that often seems to create the problem. Calling the inputNode getter once and putting it into a variable and using that instance appeared to fix the issue.