You can get more information from the ac6-tools website and download (registration required) various documents highlighting:
Peripherals registers cannot be displayed permanently because it would generate too much traffic on the debug link. Also, reading certain registers may have side effects (for UART reception registers for instance, the value may be lost after a read).
To see the values of a peripheral register, the register group it belongs to must be opened and the register must be selected by clicking on it.
The undue warning message is refering to sources from another project, it won’t affect the debugging process. The IDE indexer is checking all the open projects and some functions name might be the same between project.
If you want the message not to be displayed, close the unrelated projects.
Some USB 3.0 Controllers (such as NEC/Renesas) has bug that prevents access to USB devices. Make sure to upgrade to the latest version of the controller driver to fix this issue.
For further information, please visit : https://github.com/libusb/libusb/wiki/Windows#usb-30-support
If you get this error, first check your USB cable; some cables, like those delivered with some USB chargers, will only transfer power, but not data.
Open the Windows device manager; if your cable is correct you shoud see your board appear as a STLink dongle (under Universal Serial Bus devices).
Depending on the board (Nucleo boards as well as recent disco or eval boards) you will also see a Mbed Microcontroller device appear under Disk Drives
If you don’t see any of these, try another cable, as this may be the problem.