SOLVED
unisntalling the installed (previous to upgrade to 1.6.8 ) core Arduino SAMD 32 Bit ARM coretx M0+ 1.6.4 and re-installing it from scratch
Davide
SOLVED
unisntalling the installed (previous to upgrade to 1.6.8 ) core Arduino SAMD 32 Bit ARM coretx M0+ 1.6.4 and re-installing it from scratch
Davide