I am currently breaking my head on a crash (we are using Qt 5.14.0 and Visual Studio 2015). When running one of our Google Test unit tests, the test only sometimes fails (in my case, in 1 out of 4 runs) with an error dialog having the text:

Exception thrown: read access violation.
temp-> was 0x4C311B4
If there is a handler for this exception, the program may be safely continued.

The call stack at the time of the crash looks as follows (note that I renamed some things in order not to reveal company code):

Qt5Networkd.dll!Microsoft::WRL::ComPtr<IConnectionPoint>::InternalRelease() Line 200
Qt5Networkd.dll!Microsoft::WRL::ComPtr<IConnectionPoint>::~ComPtr<IConnectionPoint>() Line 256
Qt5Networkd.dll!QNetworkListManagerEvents::~QNetworkListManagerEvents() Line 560
[External Code]	
Qt5Networkd.dll!QNetworkListManagerEvents::Release() Line 482
Qt5Networkd.dll!Microsoft::WRL::ComPtr<QNetworkListManagerEvents>::InternalRelease() Line 200
Qt5Networkd.dll!Microsoft::WRL::ComPtr<QNetworkListManagerEvents>::Reset() Line 401
Qt5Networkd.dll!QNetworkStatusMonitorPrivate::~QNetworkStatusMonitorPrivate() Line 632
[External Code]	
Qt5Cored.dll!QScopedPointerDeleter<QObjectData>::cleanup(QObjectData * pointer=0x05342b40) Line 60
Qt5Cored.dll!QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >::~QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >() Line 107
Qt5Cored.dll!QObject::~QObject() Line 1119
Qt5Networkd.dll!QNetworkStatusMonitor::~QNetworkStatusMonitor() Line 667
Qt5Networkd.dll!QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate() Line 1927
[External Code]	
Qt5Cored.dll!QScopedPointerDeleter<QObjectData>::cleanup(QObjectData * pointer=0x05340958) Line 60
Qt5Cored.dll!QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >::~QScopedPointer<QObjectData,QScopedPointerDeleter<QObjectData> >() Line 107
Qt5Cored.dll!QObject::~QObject() Line 1119
Qt5Networkd.dll!QNetworkAccessManager::~QNetworkAccessManager() Line 535
[External Code]	
Qt5Cored.dll!QObjectPrivate::deleteChildren() Line 2123
Qt5Cored.dll!QObject::~QObject() Line 1110
[External Code]	
Qt5XmlPatternsd.dll!QPatternist::ReferenceCountedValue<QObject>::~ReferenceCountedValue<QObject>() Line 87
[External Code]	
Qt5XmlPatternsd.dll!QExplicitlySharedDataPointer<QPatternist::ReferenceCountedValue<QObject> >::~QExplicitlySharedDataPointer<QPatternist::ReferenceCountedValue<QObject> >() Line 184
[External Code]	
Qt5XmlPatternsd.dll!QXmlQuery::~QXmlQuery() Line 309
FooBarPlugins_gtest.exe!MyXPathParser::~MyXPathParser() Line 52
[External Code]	
FooBarPlugins_gtest.exe!ConfigResultGenerator::~ConfigResultGenerator() Line 77
[External Code]	
FooBarPlugins_gtest.exe!MyMockServer::~MyMockServer() Line 61
[External Code]	
FooBarPlugins_gtest.exe!MySuperTestWithSimulators::~MySuperTestWithSimulators() Line 142
[External Code]	
FooBarPlugins_gtest.exe!testing::Test::DeleteSelf_() Line 492
FooBarPlugins_gtest.exe!testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test,void>(testing::Test * object=0x01219360, void(testing::Test::*)() method=0x009087d3, const char * location=0x00d9bf98) Line 2418
FooBarPlugins_gtest.exe!testing::internal::HandleExceptionsInMethodIfSupported<testing::Test,void>(testing::Test * object=0x01219360, void(testing::Test::*)() method=0x009087d3, const char * location=0x00d9bf98) Line 2469
FooBarPlugins_gtest.exe!testing::TestInfo::Run() Line 2690
FooBarPlugins_gtest.exe!testing::TestSuite::Run() Line 2817
FooBarPlugins_gtest.exe!testing::internal::UnitTestImpl::RunAllTests() Line 5339
FooBarPlugins_gtest.exe!testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl,bool>(testing::internal::UnitTestImpl * object=0x01182490, bool(testing::internal::UnitTestImpl::*)() method=0x00901e01, const char * location=0x00d9e558) Line 2418
FooBarPlugins_gtest.exe!testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl,bool>(testing::internal::UnitTestImpl * object=0x01182490, bool(testing::internal::UnitTestImpl::*)() method=0x00901e01, const char * location=0x00d9e558) Line 2469
FooBarPlugins_gtest.exe!testing::UnitTest::Run() Line 4925
FooBarPlugins_gtest.exe!RUN_ALL_TESTS() Line 2474
FooBarPlugins_gtest.exe!main(int argc=3, char * * argv=0x01181cc8) Line 205
[External Code]	

The crash seems to occur at the end of the unit test, when the test fixture's destructor gets called. Simplifying things, I think I have the following chain of destructors (from our own code):

~MySuperTestWithSimulators()
=> calls ~MyMockServer()
  => calls ~ConfigResultGenerator()
    => calls ~MyXPathParser()
      => calls ~QXmlQuery()

Going even more up the call stack, I no longer encounter code written by us, the rest is third-party.

Given the fact that the crash only occurs 1 out of 4 times, I think I should be looking for a race-condition. However, I can't seem to find anything suspicious... So given the above error message and call stack, here are my questions:

1. Does anybody see the problem or can tell me what to look for?
2. What would you do in order to debug this further and better diagnose the problem?

Thanks!