Ulink2 is working fine in Keil4.73 and is able to program TLE9867 device but in Keil5.20 with firmware V2.03 of Ulink2 it is not able to program TLE9879 Infineon MCU. in keil4.73 even with firmware V2.03 of Ulink2 , one can program TLE9867. so conclusion is that Keil5 is not supporting programming of TLE9867 device with Ulink2.
check the error explanation here http://www.keil.com/support/man/docs/ulink2/ulink2_errors.htm A serial No. showing up only means µVision detect this ULINK2 correctly. "SWD Communication Failure" means your ULINK2 cannot communicate with your target board via SWD port correctly.
btw. where did you buy your ULINK2?
Strange then how come the same debugger is able to program with same PC using with Keil4.17 IDE via SWD port to my target board.