The Installation Guide for Boot2Qt tells users to install adb but not how to configure it in Qt Creator. Like this, Creator cannot find adb and writes error messages to "General Messages":

Boot2Qt: Error starting adb server "D:/Qt-B2Q/Tools/b2qt/adb.exe": Process failed to start: No such file or directory
Boot2Qt: Giving up.
Boot2Qt: Could not start adb server. Device detection will not work.

The documentation should tell the user to set up the correct path to adb in "Tools" -> "Options..." -> "Devices" -> "Boot to Qt" which will solve this.