The official Mbed 2 C/C++ SDK provides the software platform and libraries to build your applications.
Dependents: hello SerialTestv11 SerialTestv12 Sierpinski ... more
Issue: Target "NUCLEO-F303K8" is not recognized
You can select the Nucleo-F303K8 as a platform, but trying to compile the "Nucleo-blink-led" example ends with the above error message.
This should be now fixed.
Thanks for reporting the issue.