Opening the registers view on Qt Creator 4.0.2 works fine but if the window is left open and the debugger is restarted, the application will not run. Removing the registers view before restarting resolved the problem.

On failed start up, the debugger log shows:

Starting debugger "LldbEngine" for ABI "x86-macos-generic-mach_o-64bit"...
dStart parameters: 'debug' mode: 1
dABI: x86-macos-generic-mach_o-64bit
dLanguages: c++
dExecutable: ----
dDirectory: ----
dDebugger: /usr/bin/lldb
dProject: ----
Directories:
dRemote: :0
dSysroot:
dDebug Source Location:
dDebugger settings:
dDisplayStringLimit: 100 (default: 100)
dSelectedPluginBreakpoints: false (default: false)
dAdjustBreakpointLocations: true (default: true)
dAllPluginBreakpoints: true (default: true)
dFontSizeFollowsEditor: false (default: false)
dUseMessageBoxForSignals: true (default: true)
dUseAlternatingRowColours: false (default: false)
dLogTimeStamps: false (default: false)
dAutoQuit: false (default: false)
dSwitchModeOnExit: false (default: false)
dBreakpointsFullPath: false (default: false)
dCloseBuffersOnExit: false (default: false)
dCloseMemoryBuffersOnExit: true (default: true)
dUseDebuggingHelper: true (default: true)
dUseCodeModel: true (default: true)
dRaiseOnInterrupt: true (default: true)
dStationaryEditorWhileStepping: false (default: false)
dUseToolTipsInLocalsView: false (default: false)
dUseToolTipsInBreakpointsView: false (default: false)
dShowThreadNames: false (default: false)
dUseToolTips: true (default: true)
dUseAddressInStackView: false (default: false)
dUseToolTipsInBreakpointsView: false (default: true) ***
dUseAddressInBreakpointsView: false (default: false)
dGdbCustomDumperCommands: (default: )
dAdditionalArguments: (default: )
dAlwaysAdjustColumnWidths: true (default: true)
dExtraDumperFile: (default: )
dBreakEvent: (default: )
dBreakOnCrtDbgReport: false (default: false)
dSymbolPaths: (default: )
dSourcePaths: (default: )
dBreakOnThrow: false (default: false)
dBreakOnCatch: false (default: false)
dNoPluginBreakpoints: false (default: false)
dSelectedPluginBreakpointsPattern: .* (default: .*)
dBreakOnAbort: false (default: false)
dShowQmlObjectTree: true (default: true)
dBreakOnWarning: false (default: false)
dBreakOnFatal: false (default: false)
dQmlInspector.ShowAppOnTop: false (default: false)
dIgnoreFirstChanceAccessViolation: false (default: false)
dLoadGdbInit: true (default: true)
dCDB_Console: false (default: false)
dBreakpointCorrection: true (default: true)
dGdbStartupCommands: (default: )
dGdbPostAttachCommands: (default: )
dLoadGdbDumpers2: false (default: false)
dAttemptQuickStart: false (default: false)
dUseDynamicType: true (default: true)
dTargetAsync: false (default: false)
dWatchdogTimeout: 20 (default: 20)
dAutoEnrichParameters: true (default: true)
dIntelFlavor: false (default: false)
dIdentifyDebugInfoPackages: false (default: false)
dWarnOnReleaseBuilds: true (default: true)
dMultiInferior: false (default: false)
dShowStandardNamespace: true (default: true)
dMaximalStackDepth: 20 (default: 20)
dSortStructMembers: true (default: true)
dAutoDerefPointers: true (default: true)
dShowQtNamespace: true (default: true)
dShowQObjectNames: false (default: false)
dSkipKnownFrames: false (default: false)
dEnableReverseDebugging: false (default: false)
dMaximalStringLength: 10000 (default: 10000)
dState changed from DebuggerNotReady(0) to EngineSetupRequested(1) [master]
dQUEUE: SETUP ENGINE
dNOTE: ENGINE ILL ******
dState changed from EngineSetupRequested(1) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<54fetchRegisters(

{"token":54}

)
dNOTE: ENGINE ILL ******
dState changed from EngineShutdownRequested(19) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<55fetchRegisters(

{"token":55}

)
dNOTE: ENGINE ILL ******
dState changed from EngineShutdownRequested(19) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<56fetchRegisters(

{"token":56}

)
dNOTE: ENGINE ILL ******
dState changed from EngineShutdownRequested(19) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<57fetchRegisters(

{"token":57}

)
dNOTE: ENGINE ILL ******
dState changed from EngineShutdownRequested(19) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<58fetchRegisters(

{"token":58}

)
dNOTE: ENGINE ILL ******
dState changed from EngineShutdownRequested(19) to EngineShutdownRequested(19) [master]
dQUEUE: SHUTDOWN ENGINE
<59fetchRegisters(

{"token":59}

)
dCALL: SETUP ENGINE
dSTARTING LLDB: /usr/bin/lldb
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from EngineShutdownRequested(19) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from DebuggerFinished(22) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from DebuggerFinished(22) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from DebuggerFinished(22) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from DebuggerFinished(22) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
dCALL: SHUTDOWN ENGINE
dNOTE: ENGINE SHUTDOWN OK
dState changed from DebuggerFinished(22) to EngineShutdownOk(21) [master]
dState changed from EngineShutdownOk(21) to DebuggerFinished(22) [master]
dQUEUE: FINISH DEBUGGER
>(lldb) sc print('@\nlldbstartupok@\n')
dLLDB PROCESS ERROR: 1
dLLDB PROCESS FINISHED, status 1, exit code 9
dNOTE: FINISH DEBUGGER
dHANDLE RUNCONTROL FINISHED
sDebugger finished.
dNOTE: FINISH DEBUGGER
dNOTE: FINISH DEBUGGER
dNOTE: FINISH DEBUGGER
dNOTE: FINISH DEBUGGER
dNOTE: FINISH DEBUGGER