It is NOT always reproducible. Although the original reporter reported such issue, we have tested on multiple macOS14 devices but failed to reproduce the issue. Just in case, I filed this bug report after an internal discussion.

According to original reporter, after placing a breakpoint and starting application in debug mode (F5), the following log gets printed in loop and debugger cannot be started:

QML Debugger: Socket state changed to QAbstractSocket::HostLookupState
sQML Debugger: Socket state changed to QAbstractSocket::ConnectingState
sQML Debugger: Socket state changed to QAbstractSocket::UnconnectedState
wQML Debugger: Error: QAbstractSocket::ConnectionRefusedError

If it's true, then it sounds like "cannot connect to debugger server" issue.

One thing is that such log also happens to me - but only once. After the initial failure, debugger starts normally when trying to connect for the 2nd time.

Update: original report provided a debugger log.