This is just info to give another option for anyone having problems updating. Both Garmin and Jepp tech support personnel were stumped after recommending several steps which did not resolve the issue. This worked for me thanks to one savvy Jepp tech. Your results may vary.

Long story short.... Had a heck of a time updating the two supplemental cards (generic Sandisk 8gb). After a day in a half of trial and error, I figured it out and thought Id post my method here for others. DA42 G1000 Legacy 370.22 version TO UPDATE BOTTOM SUPPLEMENTAL CARDS G1000 legacy unit Format...