Recently, some customers have provided us with feedback stating they have been experiencing difficulties when connecting Kinetis L series microcontrollers using Multilink Universal probes, after checking the connection and software settings no obvious errors could be found. This recurrent problem has been confirmed by several customers, the problem is caused by a long connection line. My suggestion is to keep connection line length to 10cm or less; otherwise, the IDE may not be able to establish the connection through the Multilink Universal.
Thank you! I was facing this problem days and had found no solution, in my case, I could eventually write the microcontroller in use and other times not. Now I made a cable 5 cm and not used the USB MULTIKINK connector and I'm getting program the microcontroller without problems.
Microcotnrolador used: MKL15Z128VLH4