Qt Creator fails to start debugging on Mac

Question

Recently (I suspect some system/homebrew update) the Qt's debugger stopped working. It hangs forever on Setting up inferior...

The internal log:

dStart parameters: 'QGIS' mode: 1
dABI: x86-darwin-generic-mach_o-64bit
dLanguages: c++ 
dExecutable: ./QGIS 
dDirectory: ./build/output/bin/QGIS.app/Contents/MacOS
dDebugger: /Library/Developer/CommandLineTools/usr/bin/lldb
dProject: ./QGIS
dAdditional Search Directories:
dSysroot: 
dDebug Source Location: 
dDebugger settings:
dAdditionalArguments:   (default: )
dAdjustBreakpointLocations: true  (default: true)
dAllPluginBreakpoints: true  (default: true)
dAlwaysAdjustColumnWidths: true  (default: true)
dAutoDerefPointers: true  (default: true)
dAutoEnrichParameters: true  (default: true)
dAutoQuit: false  (default: false)
dBreakEvent:   (default: )
dBreakOnAbort: false  (default: false)
dBreakOnCatch: false  (default: false)
dBreakOnCrtDbgReport: false  (default: false)
dBreakOnFatal: false  (default: false)
dBreakOnThrow: false  (default: false)
dBreakOnWarning: false  (default: false)
dBreakpointCorrection: true  (default: true)
dBreakpointsFullPath: false  (default: false)
dCDB_Console: false  (default: false)
dCloseBuffersOnExit: false  (default: false)
dCloseMemoryBuffersOnExit: true  (default: true)
dDisplayStringLimit: 100  (default: 100)
dEnableReverseDebugging: false  (default: false)
dExtraDumperFile:   (default: )
dFirstChanceExceptionTaskEntry: true  (default: true)
dFontSizeFollowsEditor: false  (default: false)
dGdbCustomDumperCommands:   (default: )
dGdbPostAttachCommands:   (default: )
dGdbStartupCommands:   (default: )
dIdentifyDebugInfoPackages: false  (default: false)
dIgnoreFirstChanceAccessViolation: false  (default: false)
dIntelFlavor: false  (default: false)
dLoadGdbDumpers2: false  (default: false)
dLoadGdbInit: true  (default: true)
dLogTimeStamps: false  (default: false)
dMaximalStackDepth: 20  (default: 20)
dMaximalStringLength: 10000  (default: 10000)
dMultiInferior: false  (default: false)
dNoPluginBreakpoints: false  (default: false)
dQmlInspector.ShowAppOnTop: false  (default: false)
dRaiseOnInterrupt: true  (default: true)
dSecondChanceExceptionTaskEntry: true  (default: true)
dSelectedPluginBreakpoints: false  (default: false)
dSelectedPluginBreakpointsPattern: .*  (default: .*)
dShowQObjectNames2: true  (default: true)
dShowQmlObjectTree: true  (default: true)
dShowQtNamespace: true  (default: true)
dShowStandardNamespace: true  (default: true)
dShowThreadNames: false  (default: false)
dSkipKnownFrames: false  (default: false)
dSortStructMembers: true  (default: true)
dSourcePaths:   (default: )
dStationaryEditorWhileStepping: false  (default: false)
dSwitchModeOnExit: false  (default: false)
dSymbolPaths:   (default: )
dTargetAsync: false  (default: false)
dUseAddressInBreakpointsView: false  (default: false)
dUseAddressInStackView: false  (default: false)
dUseAlternatingRowColours: false  (default: false)
dUseCodeModel: true  (default: true)
dUseDebuggingHelper: true  (default: true)
dUseDynamicType: true  (default: true)
dUseMessageBoxForSignals: true  (default: true)
dUsePythonDumper: true  (default: true)
dUseToolTips: true  (default: true)
dUseToolTipsInBreakpointsView: false  (default: false)
dUseToolTipsInLocalsView: false  (default: false)
dUseToolTipsInStackView: true  (default: true)
dWarnOnReleaseBuilds: true  (default: true)
dWatchdogTimeout: 20  (default: 20)
dState changed from DebuggerNotReady(0) to EngineSetupRequested(1)
dCALL: SETUP ENGINE
dSTARTING LLDB: /Library/Developer/CommandLineTools/usr/bin/lldb
 Setting up inferior...
<1loadDumpers({"token":1})
<2setupInferior({"attachpid":0,"breakonmain":0,<environment suppressed>,"executable":"/Users/peter/Projects/qgis3/build-QGIS-Qt_5_12_3_5_12_3-Debug/output/bin/QGIS.app/Contents/MacOS/QGIS","nativemixed":0,"platform":"","processargs":"","remotechannel":"","startmode":1,"sysroot":"","token":2,"useterminal":0,"workingdirectory":"./output/bin/QGIS.app/Contents/MacOS"})

eERROR: Lldb stderr: error: there is no embedded script interpreter in this mode.
eerror: there is no embedded script interpreter in this mode.
eERROR: Lldb stderr: error: there is no embedded script interpreter in this mode.
eerror: there is no embedded script interpreter in this mode.

>(lldb) script sys.path.insert(1, '/Applications/Qt Creator.app/Contents/Resources/debugger/')
>(lldb) script from lldbbridge import *
>(lldb) script theDumper.loadDumpers({"token":1})
>(lldb) script theDumper.setupInferior({"attachpid":0,"breakonmain":0,"environment":["4170706c655f5075625375625f536f636b65745f52656e6465723d2f707269766174652f746d702f636f6d2e6170706c652e6c61756e6368642e523977366371596a6d642f52656e646572","434c49434f4c4f523d31","444953504c41593d2f707269766174652f746d702f636f6d2e6170706c652e6c61756e6368642e734648496356415574732f6f72672e6d61636f73666f7267652e7871756172747a3a30","484f4d453d2f55736572732f7065746572","484f4d45425245575f43433d636c616e67","484f4d45425245575f4358583d636c616e672b2b","484f4d45425245575f4e4f5f4155544f5f5550444154453d31","4c414e473d656e5f55532e5554462d38","4c435f414c4c3d656e5f55532e5554462d38","4c435f43545950453d5554462d38","4c4f474e414d453d7065746572","4f4c445057443d2f55736572732f70657465722f50726f6a656374732f71676973332f51474953","504154483d2f7573722f6c6f63616c2f7362696e3a2f7573722f6c6f63616c2f62696e3a2f7573722f62696e3a2f62696e3a2f7573722f7362696e3a2f7362696e3a2f4c6962726172792f5465582f74657862696e3a2f6f70742f5831312f62696e","5053313d5c5b5c655b33326d5c5d5c755c5b5c655b6d5c5d5c5b5c655b33326d5c5d405c5b5c655b6d5c5d5c5b5c655b33326d5c5d5c685c5b5c655b6d5c5d3a5c5b5c655b33346d5c5d5c775c5b5c655b6d5c5d5c2420","51544449523d2f7573722f6c6f63616c2f43656c6c61722f71742f352e31322e33","534543555249545953455353494f4e49443d3138366138","5348454c4c3d2f62696e2f62617368","53484c564c3d31","5353485f415554485f534f434b3d2f707269766174652f746d702f636f6d2e6170706c652e6c61756e6368642e7836626d74703371524a2f4c697374656e657273","5445524d3d787465726d2d323536636f6c6f72","5445524d5f50524f4752414d3d4170706c655f5465726d696e616c","5445524d5f50524f4752414d5f56455253494f4e3d3432312e32","5445524d5f53455353494f4e5f49443d34434644433031342d393731392d344437442d394132382d344637413739354235453632","544d504449523d2f7661722f666f6c646572732f395f2f316e747a31736778317167666c6b32707973686e74726d7230303030676e2f542f","555345523d7065746572","5850435f464c4147533d307830","5850435f534552564943455f4e414d453d6f72672e71742d70726f6a6563742e717463726561746f722e3435343736","5f3d2f7573722f62696e2f6f70656e","5f5f43465f555345525f544558545f454e434f44494e473d30783146353a3078303a307830"],"executable":"/Users/peter/Projects/qgis3/build-QGIS-Qt_5_12_3_5_12_3-Debug/output/bin/QGIS.app/Contents/MacOS/QGIS","nativemixed":0,"platform":"","processargs":"","remotechannel":"","startmode":1,"sysroot":"","token":2,"useterminal":0,"workingdirectory":"/Users/peter/Projects/qgis3/build-QGIS-Qt_5_12_3_5_12_3-Debug/output/bin/QGIS.app/Contents/MacOS"})

the relevant error is probably:

ERROR: Lldb stderr: error: there is no embedded script interpreter in this mode.

I have lldb-1100.0.25.3, MacOS 10.14.5, Qt Creator 4.9.0 (Based on Qt 5.12.2 (Clang 10.0 (Apple), 64 bit))

Answer 1

This appears to be an issue with the LLDB that comes with CLTools. A temporary workaround would be to fallback to Python 2 by setting the following default:

defaults write com.apple.dt.lldb DefaultPythonVersion 2

A more detailled explanation is that the RPATH in liblldbPluginScriptInterpreterPython3.dylib is wrong. It's failing to find the Python3 framework, which prevents LLDB from loading the scripting plugin. The directory layout is slightly different between Xcode and CLTools. Another workaround would be to use the lldb that's part of Xcode, instead of the one that comes with CLTools.

Answer 2

I had this issue today after updating to Mac OS to v12.3.1. In my case, what worked was to do what @Jonas suggested, but setting python version to 3 instead of 2:

$ defaults write com.apple.dt.lldb DefaultPythonVersion 3

This solution is more like a workaround than a fix since I still have the error but at least it does not get stuck and I am able to debug normally. Setting DefaultPythonVersion back to 2 triggers the error again.

I suspect that the issue is because I have installed an Xcode version that is not supported anymore by Mac OS v12.3.1 but is required by the QT 5.12.12 version that I am using. Updating to the most recent Xcode should fix the issue but it would require update to QT 6 which I'm not ready yet.