[KevinH]

Here is the critical tidbit;

Thread 0 Crashed:: CrBrowserMain Dispatch queue: com.apple.main-thread
0 org.qt-project.QtCore 0x0000000111dbcb94 QSysInfo::machineUniqueId() + 68
1 ??? 0x000060000140729a 0 + 105553137267354
2 org.qt-project.QtCore 0x0000000111df4e51 0x111d92000 + 405073
3 org.qt-project.QtCore 0x0000000111fda383 0x111d92000 + 2392963
4 org.qt-project.QtCore 0x0000000111df3e30 QLockFile::tryLock(std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000l> >) + 192
5 org.qt-project.QtCore 0x000000011205c6d7 0x111d92000 + 2926295
6 org.qt-project.QtCore 0x000000011205c4bf 0x111d92000 + 2925759
7 org.qt-project.QtCore 0x000000011205f8ca QSettings::~QSettings() + 42
8 com.sigil-ebook.Sigil.app 0x000000010219e6dc UpdateChecker::CheckForUpdate() + 2300
9 com.sigil-ebook.Sigil.app 0x0000000101f3d09a main + 6490
10 libdyld.dylib 0x00007fff20416f3d start + 1


It is actually crashing in Qt QSysInfo in machineUniqueId() when it is looking to see if there is a newer version of Sigil!

DiapDealer is there an easy way to disable the updateChecker?
That might just move you the issue to some other place that uses python.

I will keep digging.