Steps to reproduce:

1. Install 5.15.5 B2Qt binary (intel-corei7-64 used in testing)
2. Create a qt quick example with application wizard (Qt Quick Stack used in testing)
3. (Add the install(TARGETS app_name DESTINATION /opt) to CMakeLists.txt)
4. Disselect "Enable C++" from Debugger Settings
5. Set a QML breakpoint
6. Build and start debugging

Expected result:

Debugger starts and stops at breakpoint

Actual result:

The Debugger doesn't start and:

 14:53:28: Unable to create a debugging engine.

Invalid port value.


Malformed ports specification


Could not parse string


Invalid port range

Is shown in Application Output. The Debugger Log doesn't show any output.